SCWCD STUFF
SCWCD (SUN CERTIFIED WEB COMPONENT DEVELOPER EXAM)

1)Refer Head first -servlets and JSp book......

a)Start with Head first....divide this book in 3 main topics
i)Servlet ii) jsp iii) security n design pattern
b) make seperate note book for these topics.........
c) note down important points as well as bullets points given at the end of the
each chapters.
d) chapters 5 n 6 need special attention....try 2 explore each topic on internet n
notes down extra points. exmp...servletconfig vs
servletcontext,requestdispatcher vs
sendRedirect,httpsessionBindingListenerhttpsessionListener etc.
e)pay attention on Servlet API......
i)servlet-->GenericServlet-->HttpServlet n thier methods
ii)ServletRequest-->HttpServletRequest n their methods
iii)ServletResponse-->HttpServletResponse n their methods
Draw there Diagrams.....
f) JSTL n Custom tags r very important including TLD Files
g) filters ,Design patters n web security....r very scoring from exam point of view.its
mainly theortical
2)Refer Hanumnath Desmukh.......
a)just go though it. quickly...n note down extra points which r not given in Head
First....
3) Read Head First twice n Hanumanth Desmukh Book once....thats more than enough
4) make two separate note book for ....problems.......
a) 1st....containing servlet, Servlet Model ,filters ,design patterns , web security
b) For JSP and custom tags,JSTL......
5)Now start solving problems ....Given at the end of each chapters....n note important
question ...section wise in the note book. (SCWCD exam is having limited sets of
mocks exams n Simulators, so first concentrate on therotical n conceptual parts n
then start solving problems.Dont directly jump into the problems, after raeding
each chapters.as afterwards u will feel all questions ur solving r repeated n u
already knw their answers).
6)Do the same for Hanumnath Desmukh Book...n note imp problems.
7) now start solving Mocks Exams........
a)first....slove Sun[1].TestKing.310-080
b)then...Actualtest.com....310-080....version...12-04-07
c)ExamSheets.......(The quick way 2 get Certified)..310-080...ver..12-03-2003
d)Actualtest.com.....310-081....version..... 04-18-05
e)Actualtest.com....310-081...version....06-14-07
f)Actualtest.com....310-081...version...01-08-08
after that anything you will search on internet u will get repeated questions....
8) Refer www.javaranch.com

Some good Questions of these Mocks exams are discussed at :

http://www.coderanch.com/forums/f-18/Web-Component-Certification- SCWCD;jsessionid=8C28E7DFCDCA945D5C1BE1D9311F3535
9)start practicing on Simulators.........
a)start with...030504--WHIZLABS SUN SCWCD 310-080 EXAM SIMULATOR V4.0
DATECODE 20030421-JGT (easy one)
b)JWebPlus V4......(u will find some standards question sets which r similars 2
exams ( specially ...tough n very tough sections)
10) from exam points of view........
a)310-083-1
b)310-083-2
c)310-083-3
d)310-083ePad
r very important..as u will find maximum questions r repeated from these 4
simulators
11) finally solve .....
a) question set given at the end on HEad First....(Final Mock Exam)...if ur scoring
more than 85% in this exam...u will able 2 crack scwcd 5 exam....
12)quick notes..........
a)Study Guide.....by....Velmurugan Periasamy is very useful for quick revision..
b)similary.....web.xml file.....study guide
c)for design patterns.......PeabodyOnScwcdPatterns (if ur reading this one..u will
not miss a single question on design pattern)
13) Before ur gng 2 write exam..u should be familiar..with questions in
a) section (12)...simulators
b) head first n hanumath desmukh problems
c) final mocks exams.....
as u will find many question r repeated in exam from these parts.......
14) for online exams......
a)http://www.javaranch.com/carl/scwcd/scwcd_mock_logo.jsp
b)http://java.about.com/gi/dynamic/offsite.htm?zi=1/XJ&sdn=java&cdn=compute&tm=43&gps=153_504_1276_604&f=00&su=p284.8.150.ip_&tt=3&bt=0&bts=1&zu=http%3A//www.podar.net/scwcd/startexam.htm
c)http://www.podar.net/cgi-bin/scwcd/start.pl
15) All materials mentioned above u can download through.......
a) http://rapidshare.com/files/133553547/SCWCD_All_details.rar.html
Best of Luck...............

Typing Mistake.......

13) Before ur gng 2 write exam..u should be familiar..with questions in
a) section (12)...simulators

Correction.........

13) Before ur gng 2 write exam..u should be familiar..with questions in
a) section (10)...simulators

Some Important Links......

1)http://www.examcram2.com/practice_exams/question.asp?start=true&exam_id=25cb 6fd0-555d-4a3c-806d-227d39bb9f5f&st=43432&rl=1
2)http://www.javaprepare.com/scwd/quests/questions.html
3)http://www.podar.net/scwcd/startexam.htm
4)http://www.gayanb.com/visitlink.php?url=www.javaranch.com/carl/scwcd/scwcd_mock_logo.jsp
5)http://www.javaranch.com/carl/SCWCD.htm
6)http://www.javaranch.com/carl/scwcd/scwcd_mock.jsp
7)http://www.j2eecertificate.com/scwcd/control/runsampletest
8)http://faq.javaranch.com/view?ScwcdLinks
9)http://www.whizlabs.com/tutorial/scwcd/j-scwcd-11-4.html
10)http://saloon.javaranch.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic&f=18&t=003618
11)http://saloon.javaranch.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic&f=18&t=003611
12)http://java.sun.com/j2ee/1.4/docs/tutorial/doc/
13)http://saloon.javaranch.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic&f=18&t=003261
14)http://java.sun.com/j2ee/1.4/docs/tutorial/doc/Servlets8.html
15)http://www.enode.com/x/markup/tutorial/mvc.html
16)http://saloon.javaranch.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic&f=18&t=003442
17)http://www.informit.com/articles/article.asp?p=30946&seqNum=8
18)http://java.sun.com/j2ee/1.4/docs/tutorial/doc/JSPIntro7.html
19)http://www.jdiscuss.com/
20)http://www.javarabbit.com/menu/16
21)http://www.javaprepare.com/scwd/links.html
22)http://java.sun.com/blueprints/patterns/catalog.html
23)http://www.javaranch.com/carl/scwcd/scwcd_mock_logo.jsp
24)http://www.jpilotexam.org/downloads.html
25)http://www.javabeat.net/javabeat/forum/viewtopic.php?t=118
26)http://www.podar.net/scwcd/startexam.htm
27)http://www.j2eecertificate.com/
28)http://java.about.com/cs/javacertification/tp/freescwcd.htm
29)http://java.sun.com/products/servlet/Filters.html
30)http://java.sun.com/j2ee/1.4/docs/tutorial/doc/Servlets8.html

All Scwcd Materials......At One Place
1)Ebooks.........
http://rapidshare.com/files/203761505/Ebook.rar
2)Simulators........
http://rapidshare.com/files/203741463/Simulator.rar
3)Notes.....
http://rapidshare.com/files/203741468/Notes.rar
4)Mock Exams......
http://rapidshare.com/files/203720061/mock_exam.rar
5)Guide.....
http://rapidshare.com/files/203741465/guide.rar
6)Success Stories...
http://rapidshare.com/files/203741469/scwcd_success_stories.rar

General Questions


1.Does C# support multiple-inheritance?
No. But you can use Interfaces.

2.Where is a protected class-level variable available?
It is available to any sub-class derived from base class

3.Are private class-level variables inherited?
Yes, but they are not accessible.


4.Describe the accessibility modifier “protected internal”.
It is available to classes that are within the same assembly and derived from the specified base class.

6.Which class is at the top of .NET class hierarchy?
System.Object.

7.What does the term immutable mean?
The data value may not be changed.
Note: The variable value may be changed, but the original immutable data value was discarded and a new data value was created in memory.

8.What’s the difference between System.String and System.Text.StringBuilder classes?
System.String is immutable.
System.StringBuilder was designed with the purpose of having a mutable string where a variety of operations can be performed.

9.What’s the advantage of using System.Text.StringBuilder over System.String?

StringBuilder is more efficient in cases where there is a large amount of string manipulation. Strings are immutable, so each time a string is changed, a new instance in memory is created.

10.Can you store multiple data types in System.Array?
No.

11.What’s the difference between the System.Array.CopyTo() and System.Array.Clone()?
The Clone() method returns a new array (a shallow copy) object containing all the elements in the original array. The CopyTo() method copies the elements into another existing array. Both perform a shallow copy. A shallow copy means the contents (each array element) contains references to the same object as the elements in the original array. A deep copy (which neither of these methods performs) would create a new instance of each element's object, resulting in a different, yet identacle object.

12.How can you sort the elements of the array in descending order?
By calling Sort() and then Reverse() methods.

13.What’s the .NET collection class that allows an element to be accessed using a unique key?
HashTable.

14.What class is underneath the SortedList class?
A sorted HashTable.

15.Will the finally block get executed if an exception has not occurred?
Yes.

16.What’s the C# syntax to catch any possible exception?
A catch block that catches the exception of type System.Exception. You can also omit the parameter data type in this case and just write catch {}.

17.Can multiple catch blocks be executed for a single try statement?
No. Once the proper catch block processed, control is transferred to the finally block .

18.Explain the three services model commonly know as a three-tier application?
Presentation (UI), Business (logic and underlying code) and Data (from storage or other sources).
Class Questions


1.What is the syntax to inherit from a class in C#?
Place a colon and then the name of the base class.
Example: class MyNewClass : MyBaseClass

2.Can you prevent your class from being inherited by another class?
Yes. The keyword “sealed” will prevent the class from being inherited.

3.Can you allow a class to be inherited, but prevent the method from being over-ridden?
Yes. Just leave the class public and make the method sealed.

4.What’s an abstract class?
A class that cannot be instantiated. An abstract class is a class that must be inherited and have the methods overridden. An abstract class is essentially a blueprint for a class without any implementation.

5.When do you absolutely have to declare a class as abstract?

1. When the class itself is inherited from an abstract class, but not all base abstract methods have been overridden.

2. When at least one of the methods in the class is abstract.


6.What is an interface class?
Interfaces, like classes, define a set of properties, methods, and events. But unlike classes, interfaces do not provide implementation. They are implemented by classes, and defined as separate entities from classes.

7.Why can’t you specify the accessibility modifier for methods inside the interface?
They all must be public, and are therefore public by default.

8.Can you inherit multiple interfaces?
Yes. .NET does support multiple interfaces.

9.What happens if you inherit multiple interfaces and they have conflicting method names?
It’s up to you to implement the method inside your own class, so implementation is left entirely up to you. This might cause a problem on a higher-level scale if similarly named methods from different interfaces expect different data, but as far as compiler cares you’re okay.

10. What’s the difference between an interface and abstract class?
In an interface class, all methods are abstract - there is no implementation. In an abstract class some methods can be concrete. In an interface class, no accessibility modifiers are allowed. An abstract class may have accessibility modifiers.

11. What is the difference between a Struct and a Class?
Structs are value-type variables and are thus saved on the stack, additional overhead but faster retrieval. Another difference is that structs cannot inherit.
Method and Property Questions


1. What’s the implicit name of the parameter that gets passed into the set method/property of a class?
Value. The data type of the value parameter is defined by whatever data type the property is declared .

2. What does the keyword “virtual” declare for a method or property?
The method or property can be overridden.

3. How is method overriding different from method overloading?
When overriding a method, you change the behavior of the method for the derived class. Overloading a method simply involves having another method with the same name within the class.

4. Can you declare an override method to be static if the original method is not static?
No. The signature of the virtual method must remain the same. (Note: Only the keyword virtual is changed to keyword override)

5. What are the different ways a method can be overloaded?
Different parameter data types, different number of parameters, different order of parameters.

6. If a base class has a number of overloaded constructors, and an inheriting class has a number of overloaded constructors; can you enforce a call from an inherited constructor to a specific base constructor?
Yes, just place a colon, and then keyword base (parameter list to invoke the appropriate constructor) in the overloaded constructor definition inside the inherited class.
Events and Delegates


1. What’s a delegate?
A delegate object encapsulates a reference to a method.

2. What’s a multicast delegate?
A delegate that has multiple handlers assigned to it. Each assigned handler (method) is called.

3. What’s the implicit name of the parameter that gets passed into the class’ set method?
Value, and it’s datatype depends on whatever variable we’re changing.

4. How do you inherit from a class in C#?
Place a colon and then the name of the base class.

5. Does C# support multiple inheritance?
No, use interfaces instead.

6. When you inherit a protected class-level variable, who is it available to?
Classes in the same namespace.

7. Are private class-level variables inherited?
Yes, but they are not accessible, so looking at it you can honestly say that they are not inherited.

8. Describe the accessibility modifier protected internal.?
It’s available to derived classes and classes within the same Assembly (and naturally from the base class it’s declared in).

9. C# provides a default constructor for me. I write a constructor that takes a string as a parameter, but want to keep the no parameter one. How many constructors should I write?
Two. Once you write at least one constructor, C# cancels the freebie constructor, and now you have to write one yourself, even if there’s no implementation in it.

10. What’s the top .NET class that everything is derived from?
System.Object.

11. How’s method overriding different from overloading?
When overriding, you change the method behavior for a derived class. Overloading simply involves having a method with the same name within the class.

12. What does the keyword virtual mean in the method definition?
The method can be over-ridden.

13. Can you declare the override method static while the original method is non-static?
No, you can’t, the signature of the virtual method must remain the same, only the keyword virtual is changed to keyword override.

14. Can you override private virtual methods?
No, moreover, you cannot access private methods in inherited classes, have to be protected in the base class to allow any sort of access.

15. Can you prevent your class from being inherited and becoming a base class for some other classes?
Yes, that’s what keyword sealed in the class definition is for. The developer trying to derive from your class will get a message: cannot inherit from Sealed class WhateverBaseClassName.
It’s the same concept as final class in Java.

16. Can you allow class to be inherited, but prevent the method from being over-ridden?
Yes, just leave the class public and make the method sealed.

17. What’s an abstract class?
A class that cannot be instantiated. A concept in C++ known as pure virtual method. A class that must be inherited and have the methods over-ridden.
Essentially, it’s a blueprint for a class without any implementation.

18. When do you absolutely have to declare a class as abstract (as opposed to free-willed educated choice or decision based on UML diagram)?
When at least one of the methods in the class is abstract. When the class itself is inherited from an abstract class, but not all base abstract methods have been over-ridden.

19. What’s an interface class?
It’s an abstract class with public abstract methods all of which must be implemented in the inherited classes.

20. Why can’t you specify the accessibility modifier for methods inside the interface?
They all must be public. Therefore, to prevent you from getting the false impression that you have any freedom of choice, you are not allowed to specify any accessibility, it’s public by default.

21. Can you inherit multiple interfaces?
Yes, why not.

22. And if they have conflicting method names?
It’s up to you to implement the method inside your own class, so implementation is left entirely up to you.
This might cause a problem on a higher-level scale if similarly named methods from different interfaces expect different data, but as far as compiler cares you’re okay.

23. What’s the difference between an interface and abstract class?
In the interface all methods must be abstract, in the abstract class some methods can be concrete. In the interface no accessibility modifiers are allowed, which is ok in abstract classes.

24. How can you overload a method?
Different parameter data types, different number of parameters, different order of parameters.

25. If a base class has a bunch of overloaded constructors, and an inherited class has another bunch of overloaded constructors, can you enforce a call from an inherited constructor to an arbitrary base constructor?
Yes, just place a colon, and then keyword base (parameter list to invoke the appropriate constructor) in the overloaded constructor definition inside the inherited class.

26. What’s the difference between System.String and System.StringBuilder classes?
System.String is immutable, System.StringBuilder was designed with the purpose of having a mutable string where a variety of operations can be performed.

27. Is it namespace class or class namespace?
The .NET class library is organized into namespaces. Each namespace contains a functionally related group of classes so natural namespace comes first.

Data Structure Interview Questions
• A list is ordered from smaller to largest when sort is called. Which sort would take longest time to execute?
• A list is ordered from smaller to largest when sort is called. Which sort would take shortest time to execute?
• Convert following infix _expression to post fix notation ((a+2)*(b+4)) -1 (Similar types can be asked)
• Evaluate following prefix _expression ” ++ + – (Similar types can be asked)
• Explain about types of linked lists
• Explain binary searching, Fibinocci search.
• Explain quick sort and merge sort algorithms and derive time-constraint relation for these.
• How is it possible to insert different type of elements in stack?
• How many different binary trees and binary search trees can be made from three nodes that contain key values 2 & 3?
• How will inorder, preorder and postorder traversals print elements of tree?
• How would you sort linked list?
• In which data structure, elements can be added or removed at either end, but not in middle?
• Parenthesis are never needed in prefix or postfix expressions. Why?
• Stack can be described as pointer. Explain.
• The element being searched for is not found in array of elements. What is average number of comparisons needed in sequential search to determine that element is not there, if elements are completely unordered?
• What data structure would you mostly likely see in non recursive implementation of recursive algorithm?
• What do you mean by Base case, Recursive case, Binding Time, Run-Time Stack and Tail Recursion?
• What do you mean by: * Syntax Error * Logical Error * Runtime Error How can you correct these errors?
• What does abstract data type means?
• What is average number of comparisons in sequential search?
• What is average number of comparisons needed in sequential search to determine position of element in array of elements, if elements are ordered from largest to smallest?
• What is data structure?
• What is maximum total number of nodes in tree that has N levels? Note that root is level (zero)
• When will you sort array of pointers to list elements, rather than sorting elements themselves?
• Which data structure is needed to convert infix notations to post fix notations?
• Which one is faster? binary search of orderd set of elements in array or sequential search of elements.
• Which sort show best average behavior?
• Write Binary Search program
• Write programs for Bubble Sort, Quick sort
• Write programs for Linked List (Insertion and Deletion) operations

C Programming Interview Questions
• Are expressions arr and *arr same for array of integers?
• Are variables argc and argv are local to main?
• Bitwise operator for checking whether particular bit is on or off?
• Bitwise operator for putting on particular bit in number?
• Bitwise operator for turning off particular bit in number?
• Can Structure contain Pointer to itself?
• Can there be at least some solution to determine number of arguments passed to variable argument list function?
• Can we specify variable field width in scanf() format string? If possible how?
• Can you dynamically allocate arrays in expanded memory?
• Can you use function fprintf() to display output on screen?
• Can you write function similar to printf()?
• Describe about storage allocation and scope of global, extern, static, local and register variables?
• Difference : Strings and Arrays?
• Difference : Structure and Unions?
• Difference : arrays and linked list?
• Difference : enumeration and set of pre-processor # defines?
• Difference : functions memmove() and memcpy()?
• Difference : functions rand(), random(), srand() and randomize()?
• Difference : main() in C and main() in C++?
• Difference : pass by reference and pass by value?
• Difference : strdup and strcpy?
• Differentiate between for loop and while loop? it uses?
• Does mentioning array name gives base address in all contexts?
• Does there exist any other function that can be used to convert integer or float to string?
• Does there exist any way to make command line arguments available to other functions without passing them as arguments to function?
• Explain one method to process entire string as one unit?
• How are Structure passing and returning implemented by complier?
• How can called function determine number of arguments that have been passed to it?
• How can we check whether contents of two structure variables are same or not?
• How can we read/write Structures from/to data files?
• How much maximum can you allocate in single call to malloc()?
• How will you declare array of three function pointers where each function receives two ints and returns float?
• If we want that any wildcard characters in command line arguments should be appropriately expanded, are we required to make any special provision? If yes, that?
• In header file whether functions are declared or defined?
• In header files whether functions are declared or defined?
• Increase size of dynamically allocated array?
• Increase size of statically allocated array?
• Out of fgets() and gets() that function is safe to use and why?
• Program : compare two strings without using strcmp() function.
• Program : concatenate two strings.
• Program : find Factorial of number.
• Program : generate Fibonacci Series?
• Program : interchange variables without using third one.
• Program : s for String Reversal. same for Palindrome check.
• Program : that employs Recursion?
• Program : that uses command line arguments.
• Program : that uses functions like strcmp(), strcpy(), etc.
• To that numbering system can binary number be easily converted to?
• Use bsearch() function to search name stored in array of pointers to string?
• Use functions fseek(), freed(), fwrite() and ftell()?
• Use functions memcpy(), memset(), memmove()?
• Use functions randomize() and random()?
• Use functions sin(), pow(), sqrt()?
• Use qsort() function to sort array of structures?
• Use qsort() function to sort name stored in array of pointers to string?
• What advantages of using Unions?
• What do functions atoi(), itoa() and gcvt() do?
• What do ‘c’ and ‘v’ in argc and argv stand for?
• What does error ‘Null Pointer Assignment’ mean and what causes this error?
• What does static variable mean?
• What is NULL Macro? Difference : NULL Pointer and NULL Macro?
• What is NULL Pointer? Whether it is same as uninitialized pointer?
• What is far pointer? where we use it?
• What is linklist and why do we use it when we have arrays? – I feel correct answer should be linklist is used in cases where you don’t know memory required to store data structure and need to allocate is dynamically on demand.
• What is maximum combined length of command line arguments including space between adjacent arguments?
• What is near, far and huge pointers? How many bytes are occupied by them?
• What is object file? How can you access object file?
• What is pointer?
• What is recursion?
• What is similarity between Structure, Union and enumeration?
• What is static identifier?
• What is structure?
• What is use of typedef?
• When reallocating memory if any other pointers point into same piece of memory do you have to readjust these other pointers or do they get readjusted automatically?
• Where are auto variables stored?
• Where does global, static, local, register variables, free memory and C Program instructions get stored?
• Write down equivalent pointer expression for referring same element a[i][j][k][l]?
• advantages of using pointers in program?
• advantages of using typedef in program?
• bit fields? What is use of bit fields in Structure declaration?
• declare following: array of three pointers to chars, array of three char pointers, pointer to array of three chars, pointer to function that receives int pointer and returns float pointer, pointer to function that receives nothing and returns nothing
• detect loop in linked list?
• differences between malloc() and calloc()?
• differences between structures and arrays?
• different storage classes in C?
• dynamically allocate one-dimensional and two-dimensional array of integers?
• enumerations?
• implement substr() function that extracts sub string from given string?
• macros? advantages and disadvantages?
• obtain current time and Difference : two times?
• obtain segment and offset addresses from far address of memory location?
• print string on printer?
• register variables? advantage of using register variables?
• that function should be used to free memory allocated by calloc()?
• that header file should you include if you are to develop function that can accept variable number of arguments?

Operating System Interview Questions
• Demand paging, page faults, replacement algorithms, thrashing, etc.
• Describe different job scheduling in operating systems.
• Difference : Primary storage and secondary storage?
• Difference : multi threading and multi tasking?
• Differentiate : Complier and Interpreter?
• Differentiate : RAM and ROM?
• Explain about paged segmentation and segment paging
• Explain briefly about, processor, assembler, compiler, loader, linker and functions executed by them.
• Explain difference : microkernel and macro kernel.
• Give an example of microkernel.
• If two processes which shares same system memory and system clock in a distributed system, What is it called?
• What are basic functions of an operating system?
• What are difference phases of software development? Explain briefly?
• What are different functions of Syntax phase, Sheduler?
• What are different tasks of Lexical analysis?
• What are main difference : Micro-Controller and Micro- Processor?
• What do you mean by deadlock?
• What is DRAM? In which form does it store data?
• What is a Real-Time System ?
• What is a mission critical system ?
• What is cache memory?
• What is hard disk and what is its purpose?
• What is multi tasking, multi programming, multi threading?
• What is software life cycle?
• What is difference : Hard and Soft real-time systems ?
• What is important aspect of a real-time system ?
• What is state of processor, when a process is waiting for some event to occur?
• When would you choose bottom up methodology?
• When would you choose top down methodology?
• Which is best page replacement algorithm and Why? How much time is spent usually in each phases and why?
• While running DOS on a PC, which command would be used to duplicate entire diskette?
• Why paging is used ?
• Write a small dc shell script to find number of FF in design.

Advanced Java Programming Interview Questions
• Can we sent objects using Sockets?
• Can we use threads in Servelets?
• Can you modify an object in corba?
• Difference : CGI and Servlet?
• Difference : RMI registry and OS Agent?
• Difference : Servelets and Applets?
• Difference : applet and application?
• Difference : java class and bean?
• Explain RMI Architecture?
• Explain about RMI Architecture?
• How can you push data from an Applet to a Servlet?
• How do you call an Applet using Java Script Function?
• How do you communicate between two applets?
• How do you communicate in between Applets and Servlets?
• How do you initialize an Applet?
• How do you invoke a Servelet? Difference : doPost method and doGet method?
• How do you load an image in a Servelet?
• How do you pass parameters in RMI? Why do you serialize?
• How do you pass values from htm page to the servlet?
• How do you perform truncation using JDBC?
• How do you swing an applet?
• If you are truncated using JDBC , how can you that how much data is truncated?
• In RMI ,server object is first loaded into memory and then the stub reference is sent to the client. true or false?
• In the servlets, we are having a web page that is invoking servlets ,username and password? which is checks in database? Suppose the second page also if we want to verify the same information whether it will connect to the database or it will be used previous information?
• Suppose server object not loaded into the memory and the client request for it. What will happen?
• To a server method, the client wants to send a value with this value exceeds to a message should be sent to the client . What will you do for achieving this?
• What are 4 drivers available in JDBC? At what situation are four of the drivers used?
• What are Servelets?
• What are the difference between RMI and CORBA?
• What are the difference between RMI and Servelets?
• What do you mean by Socket Programming?
• What is CORBA?
• What is ODBC and JDBC? How do you connect the Database?
• What is RMI and what are the services in RMI?
• What is RMI?
• What is Servlet API used for connecting database?
• What is bean? Where can it be used?
• What is difference between Generic Servlet and HTTP Servelet?
• What is difference between the HTTP Servelet and Generic Servelet? Explain about their methods and parameters?
• What is purpose of applet programming?
• What is the RMI and Socket?
• What is the latest version of JDBC? What are the new features added in that?
• What is the order of method invocation in an Applet?
• What is the use of servlets?
• What is the web server used for running the servelets?
• What you mean by COM and DCOM?
• Write a program on RMI and JDBC using Stored Procedure?
• what is e-commerce?

Java Programming Interview Questions
• Can you load server object dynamically? If so what are 3 major steps involved in it?
• Can you run product development on all operating systems?
• Considering notepad/IE or any other thing as process, What will happen if you start notepad or IE 3 times ? Where three processes are started or three threads are started?
• Difference : AWT and Swing?
• Difference : Abstract class and Interface?
• Difference : Grid and Gridbaglayout?
• Difference : Process and Thread?
• Difference : java and c++?
• Difference : process and threads?
• Does java support function overloading, pointers, structures, unions or linked lists?
• Does java support multiple inheritance? if not, what is solution?
• Explain 2-tier and 3-tier architecture?
• Explain about version control?
• Have you ever used HashTable and Directory?
• How can two threads be made to communicate with each other?
• How can we do validation of fields in project?
• How can you know about drivers and database information ?
• How do you download stubs from Remote place?
• How does thread synchronization occur in monitor?
• How java can be connected to database?
• How will you add panel to frame?
• I want to store more than objects in remote server? Which methodology will follow?
• In container there are 5 components. I want to display all component names, how will you do that?
• In htm form I have button which makes us to open another page in seconds. How will you do that?
• In htm page form I have one button which makes us to open new page in seconds. How will you do that?
• Is there any tag in htm to upload and download files?
• Meaning of Servelet? What are parameters of service method?
• Meaning of Session? Explain something about HTTP Session Class?
• Meaning of Static query and Dynamic query?
• Meaning of class loader? How many types are there? When will we use them?
• Meaning of cookies? Explain main features?
• Meaning of distributed application? Why are we using that in our application?
• Meaning of flickering?
• Meaning of function overloading and function overriding?
• Suppose if we have variable ‘I’ in run method, if I can create one or more thread each thread will occupy separate copy or same variable will be shared?
• Tell some latest versions in JAVA related areas?
• What are JVM.JRE, J2EE, JNI?
• What are Normalization Rules? Define Normalization?
• What are abstract classes?
• What are adapter classes?
• What are advantages of java over C++?
• What are benefits if Swing over AWT?
• What are byte codes?
• What are files generated after using IDL to java compiler?
• What are session variable in servlets?
• What are statements in Java?
• What are streams?
• What are swing components?
• What are traverses in binary tree?
• What are virtual functions?
• What do you know about garbage collector?
• What do you mean by light weight and heavy weight components?
• What do you mean by multithreading?
• What is JAR file?
• What is JFC?
• What is JNI?
• What is base class for all swing components?
• What is client server computing?
• What is constructor and virtual function? Can we call virtual function in constructor?
• What is corresponding layout for card in swing?
• What is difference abstract class and interface?
• What is exact difference in between Unicast and Multicast object? Where will it be used?
• What is functionability stubs and skeletons?
• What is functionality of stub?
• What is interface?
• What is layout for toolbar?
• What is light weight component?
• What is main functionality of Prepared Statement?
• What is main functionality of remote reference layer?
• What is mapping mechanism used by java to identify IDL language?
• What is middleware? What is functionality of web server?
• What is polymorphism?
• What is protocol used by server and client?
• What is role of Web Server?
• What is root class for all java classes?
• What is serializable interface?
• What is serialization?
• What is thread?
• What is update method called?
• What is use of interface?
• What is user defined exception?
• When will you use interface and abstract class?
• Where are card layouts used?
• Why do we use oops concepts? What is its advantage?
• Why do you canvas?
• Why does java not support multiple inheritance?
• Why is java not fully objective oriented?
• Why is java not pure oops?
• Why java is considered as platform independent?
• Why there are some null interface in JAVA? What does it mean? Give some null interface in JAVA?
• Write down how will you create Binary tree?
• Write program for recursive traverse?
• what is meant wrapper classes?

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What is blocking and how would you troubleshoot it?
Blocking happens when one connection from an application holds a lock and a second connection requires a conflicting lock type. This forces the second connection to wait, blocked on the first.
Read up the following topics in SQL Server books online: Understanding and avoiding blocking, Coding efficient transactions.
Explain CREATE DATABASE syntax
Many of us are used to craeting databases from the Enterprise Manager or by just issuing the command: CREATE DATABAE MyDB. But what if you have to create a database with two filegroups, one on drive C and the
other on drive D with log on drive E with an initial size of 600 MB and with a growth factor of 15%? That's why being a DBA you should be familiar with the CREATE DATABASE syntax. Check out SQL Server books online for more information.
How to restart SQL Server in single user mode? How to start SQL Server in minimal configuration mode?
SQL Server can be started from command line, using the SQLSERVR.EXE. This EXE has some very important parameters with which a DBA should be familiar with. -m is used for starting SQL Server in single user mode
and -f is used to start the SQL Server in minimal confuguration mode. Check out SQL Server books online for more parameters and their explanations.
As a part of your job, what are the DBCC commands that you commonly use for database maintenance?
DBCC CHECKDB, DBCC CHECKTABLE, DBCC CHECKCATALOG, DBCC CHECKALLOC, DBCC SHOWCONTIG, DBCC SHRINKDATABASE, DBCC SHRINKFILE etc. But there are a whole load of DBCC commands which are very useful for DBAs.
Check out SQL Server books online for more information.
What are statistics, under what circumstances they go out of date, how do you update them?
Statistics determine the selectivity of the indexes. If an indexed column has unique values then the selectivity of that index is more, as opposed to an index with non-unique values. Query optimizer uses these indexes in determining whether to choose an index or not while executing a query.
Some situations under which you should update statistics:
1) If there is significant change in the key values in the index
2) If a large amount of data in an indexed column has been added, changed, or removed (that is, if the distribution of key values has changed), or the table has been truncated using the TRUNCATE TABLE statement and then repopulated
3) Database is upgraded from a previous version
Look up SQL Server books online for the following commands: UPDATE STATISTICS, STATS_DATE, DBCC SHOW_STATISTICS, CREATE STATISTICS, DROP STATISTICS, sp_autostats, sp_createstats, sp_updatestats
What are the different ways of moving data/databases between servers and databases in SQL Server?
There are lots of options available, you have to choose your option depending upon your requirements. Some of the options you have are: BACKUP/RESTORE, dettaching and attaching databases, replication, DTS, BCP, logshipping, INSERT...SELECT, SELECT...INTO, creating INSERT scripts to generate data.
Explian different types of BACKUPs avaialabe in SQL Server? Given a particular scenario, how would you go about choosing a backup plan?
Types of backups you can create in SQL Sever 7.0+ are Full database backup, differential database backup, transaction log backup, filegroup backup. Check out the BACKUP and RESTORE commands in SQL Server books online. Be prepared to write the commands in your interview. Books online also has information on detailed
backup/restore architecture and when one should go for a particular kind of backup.
What is database replication? What are the different types of replication you can set up in SQL Server?
Replication is the process of copying/moving data between databases on the same or different servers. SQL Server supports the following types of replication scenarios:
* Snapshot replication
* Transactional replication (with immediate updating subscribers, with queued updating subscribers)
* Merge replication
See SQL Server books online for indepth coverage on replication. Be prepared to explain how different replication agents function, what are the main system tables used in replication etc.
How to determine the service pack currently installed on SQL Server?
The global variable @@Version stores the build number of the sqlservr.exe, which is used to determine the service pack installed. To know more about this process visit SQL Server service packs and
versions.
What are cursors? Explain different types of cursors. What are the disadvantages of cursors? How can you avoid cursors?
Cursors allow row-by-row prcessing of the resultsets.
Types of cursors: Static, Dynamic, Forward-only, Keyset-driven. See books online for more information.
Disadvantages of cursors: Each time you fetch a row from the cursor, it results in a network roundtrip, where as a normal SELECT query makes only one rowundtrip, however large the resultset is. Cursors are also costly because they require more resources and temporary storage (results in more IO operations). Furthere, there are restrictions on the SELECT statements that can be used with some types of cursors.
Most of the times, set based operations can be used instead of cursors. Here is an example:
If you have to give a flat hike to your employees using the following criteria:
Salary between 30000 and 40000 -- 5000 hike
Salary between 40000 and 55000 -- 7000 hike
Salary between 55000 and 65000 -- 9000 hike
In this situation many developers tend to use a cursor, determine each employee's salary and update his salary according to the above formula. But the same can be achieved by multiple update statements or can be combined in a single UPDATE statement as shown below:
UPDATE tbl_emp SET salary =
CASE WHEN salary BETWEEN 30000 AND 40000 THEN salary + 5000
WHEN salary BETWEEN 40000 AND 55000 THEN salary + 7000
WHEN salary BETWEEN 55000 AND 65000 THEN salary + 10000
END
Another situation in which developers tend to use cursors: You need to call a stored procedure when a column in a particular row meets certain condition. You don't have to use cursors for this. This can be achieved using WHILE loop, as long as there is a unique key to identify each row. For examples of using WHILE loop for row by row processing, check out the 'My code library' section of my site or search for WHILE.
Write down the general syntax for a SELECT statements covering all the options.
Here's the basic syntax: (Also checkout SELECT in books online for advanced syntax).
SELECT select_list
[INTO new_table_]
FROM table_source
[WHERE search_condition]
[GROUP BY group_by__expression]
[HAVING search_condition]
[ORDER BY order__expression [ASC | DESC] ]
What is a join and explain different types of joins.
Joins are used in queries to explain how different tables are related. Joins also let you select data from a table depending upon data from another table.
Types of joins: INNER JOINs, OUTER JOINs, CROSS JOINs. OUTER JOINs are further classified as LEFT OUTER JOINS, RIGHT OUTER JOINS and FULL OUTER JOINS.
For more information see pages from books online titled: "Join Fundamentals" and "Using Joins".
Can you have a nested transaction?
Yes, very much. Check out BEGIN TRAN, COMMIT, ROLLBACK, SAVE TRAN and @@TRANCOUNT
What is an extended stored procedure? Can you instantiate a COM object by using T-SQL?
An extended stored procedure is a function within a DLL (written in a programming language like C, C++ using Open Data Services (ODS) API) that can be called from T-SQL, just the way we call normal stored procedures using the EXEC statement. See books online to learn how to create extended stored procedures and how to add them to SQL Server.
Yes, you can instantiate a COM (written in languages like VB, VC++) object from T-SQL by using sp_OACreate stored procedure. Also see books online for sp_OAMethod, sp_OAGetProperty, sp_OASetProperty, sp_OADestroy. For an example of creating a COM object in VB and calling it from T-SQL, see 'My code library' section of this site.
What is the system function to get the current user's user id?
USER_ID(). Also check out other system functions like USER_NAME(), SYSTEM_USER, SESSION_USER, CURRENT_USER, USER, SUSER_SID(), HOST_NAME().
What are triggers? How many triggers you can have on a table? How to invoke a trigger on demand?
Triggers are special kind of stored procedures that get executed automatically when an INSERT, UPDATE or DELETE operation takes place on a table.
In SQL Server 6.5 you could define only 3 triggers per table, one for INSERT, one for UPDATE and one for DELETE. From SQL Server 7.0 onwards, this restriction is gone, and you could create multiple triggers per each action. But in 7.0 there's no way to control the order in which the triggers fire. In SQL Server 2000 you could specify which trigger fires first or fires last using sp_settriggerorder
Triggers can't be invoked on demand. They get triggered only when an Associated action (INSERT, UPDATE, DELETE) happens on the table on which they are defined.
Triggers are generally used to implement business rules, auditing. Triggers can also be used to extend the referential integrity checks, but wherever possible, use constraints for this purpose, instead of triggers, as constraints are much faster.
Till SQL Server 7.0, triggers fire only after the data modification operation happens. So in a way, they are called post triggers. But in SQL Server 2000 you could create pre triggers also. Search SQL Server 2000 books online for INSTEAD OF triggers.
Also check out books online for 'inserted table', 'deleted table' and COLUMNS_UPDATED()
There is a trigger defined for INSERT operations on a table, in an OLTP system. The trigger is written to instantiate a COM object and pass the newly insterted rows to it for some custom processing. What do you think of this implementation? Can this be implemented better?
Instantiating COM objects is a time consuming process and since you are doing it from within a trigger, it slows down the data insertion process. Same is the case with sending emails from triggers. This scenario can be better implemented by logging all the necessary data into a separate table, and have a job which periodically checks this table and does the needful.
What is a self join? Explain it with an example.
Self join is just like any other join, except that two instances of the same table will be joined in the query. Here is an example:
Employees table which contains rows for normal employees as well as managers. So, to find out the managers of all the employees, you need a self join.
CREATE TABLE emp
(
empid int,
mgrid int,
empname char(10)
)
INSERT emp SELECT 1,2,'Vyas'
INSERT emp SELECT 2,3,'Mohan'
INSERT emp SELECT 3,NULL,'Shobha'
INSERT emp SELECT 4,2,'Shridhar'
INSERT emp SELECT 5,2,'Sourabh'
SELECT t1.empname [Employee], t2.empname [Manager]
FROM emp t1, emp t2
WHERE t1.mgrid = t2.empid
Here's an advanced query using a LEFT OUTER JOIN that even returns the employees without managers (super bosses)
SELECT t1.empname [Employee], COALESCE(t2.empname, 'No manager') [Manager]
FROM emp t1
LEFT OUTER JOIN
emp t2
ON
t1.mgrid = t2.empid

What is normalization? Explain different levels of normalization?
Check out the article Q100139 from Microsoft knowledge base and of course, there's much more information available in the net. It'll be a good idea to get a hold of any RDBMS fundamentals text book, especially the one by C. J. Date. Most of the times, it will be okay
if you can explain till third normal form.
What is denormalization and when would you go for it?
As the name indicates, denormalization is the reverse process of normalization. It's the controlled introduction of redundancy in to the database design. It helps improve the query performance as the number of joins could be reduced.
How do you implement one-to-one, one-to-many and many-to-many relationships while designing tables?
One-to-One relationship can be implemented as a single table and rarely as two tables with primary and foreign key relationships. One-to-Many relationships are implemented by splitting the data into two tables with primary key and foreign key relationships. Many-to-Many relationships are implemented using a junction table with the keys from both the tables forming the composite primary key of the junction table.
It will be a good idea to read up a database designing fundamentals text book.
What's the difference between a primary key and a unique key?
Both primary key and unique enforce uniqueness of the column on which they are defined. But by default primary key creates a clustered index on the column, where are unique creates a nonclustered index by default. Another major difference is that, primary key doesn't allow NULLs, but unique key allows one NULL only.
What are user defined datatypes and when you should go for them?
User defined datatypes let you extend the base SQL Server datatypes by providing a descriptive name, and format to the database. Take for example, in your database, there is a column called Flight_Num which appears in many tables. In all these tables it should be varchar(8).
In this case you could create a user defined datatype called Flight_num_type of varchar(8) and use it across all your tables.
See sp_addtype, sp_droptype in books online.
What is bit datatype and what's the information that can be stored inside a bit column?
Bit datatype is used to store boolean information like 1 or 0 (true or false). Untill SQL Server 6.5 bit datatype could hold either a 1 or 0 and there was no support for NULL. But from SQL Server 7.0 onwards, bit datatype can represent a third state, which is NULL.
Define candidate key, alternate key, composite key.
A candidate key is one that can identify each row of a table uniquely. Generally a candidate key becomes the primary key of the table. If the table has more than one candidate key, one of them will become the primary key, and the rest are called alternate keys.
A key formed by combining at least two or more columns is called composite key.
What are defaults? Is there a column to which a default can't be bound?
A default is a value that will be used by a column, if no value is supplied to that column while inserting data. IDENTITY columns and timestamp columns can't have defaults bound to them. See CREATE DEFUALT in books online.
What is a transaction and what are ACID properties?
A transaction is a logical unit of work in which, all the steps must be performed or none. ACID stands for Atomicity, Consistency, Isolation, Durability. These are the properties of a transaction. For more information and explanation of these properties, see SQL Server books online or any RDBMS fundamentals text book.
Explain different isolation levels
An isolation level determines the degree of isolation of data between concurrent transactions. The default SQL Server isolation level is Read Committed. Here are the other isolation levels (in the ascending order of isolation): Read Uncommitted, Read Committed, Repeatable Read, Serializable. See SQL Server books online for an explanation of the isolation levels. Be sure to read about SET TRANSACTION ISOLATION LEVEL, which lets you customize the isolation level at the connection level.
CREATE INDEX myIndex ON myTable(myColumn)
What type of Index will get created after executing the above statement?
Non-clustered index. Important thing to note: By default a clustered index gets created on the primary key, unless specified otherwise.
What's the maximum size of a row?
8060 bytes. Don't be surprised with questions like 'what is the maximum number of columns per table'. Check out SQL Server books online for the page titled: "Maximum Capacity Specifications".
Explain Active/Active and Active/Passive cluster configurations
Hopefully you have experience setting up cluster servers. But if you don't, at least be familiar with the way clustering works and the two clusterning configurations Active/Active and Active/Passive. SQL Server books online has enough information on this topic and there is a good white paper available on Microsoft site.
Explain the architecture of SQL Server
This is a very important question and you better be able to answer it if consider yourself a DBA. SQL Server books online is the best place to read about SQL Server architecture. Read up the chapter dedicated to SQL Server Architecture.
What is lock escalation?
Lock escalation is the process of converting a lot of low level locks (like row locks, page locks) into higher level locks (like table locks). Every lock is a memory structure too many locks would mean, more memory being occupied by locks. To prevent this from happening, SQL Server escalates the many fine-grain locks to fewer coarse-grain locks. Lock escalation threshold was definable in SQL Server 6.5, but from SQL Server 7.0 onwards it's dynamically managed by SQL Server.
What's the difference between DELETE TABLE and TRUNCATE TABLE commands?
DELETE TABLE is a logged operation, so the deletion of each row gets logged in the transaction log, which makes it slow. TRUNCATE TABLE also deletes all the rows in a table, but it won't log the deletion of each row, instead it logs the deallocation of the data pages of the table, which makes it faster. Of course, TRUNCATE TABLE can be rolled back.
Explain the storage models of OLAP
Check out MOLAP, ROLAP and HOLAP in SQL Server books online for more infomation.
What are the new features introduced in SQL Server 2000 (or the latest release of SQL Server at the time of your interview)? What changed between the previous version of SQL Server and the current version?
This question is generally asked to see how current is your knowledge. Generally there is a section in the beginning of the books online titled "What's New", which has all such information. Of course, reading just that is not enough, you should have tried those things to better answer the questions. Also check out the section titled
"Backward Compatibility" in books online which talks about the changes that have taken place in the new version.
What are constraints? Explain different types of constraints.
Constraints enable the RDBMS enforce the integrity of the database automatically, without needing you to create triggers, rule or defaults.
Types of constraints: NOT NULL, CHECK, UNIQUE, PRIMARY KEY, FOREIGN KEY
For an explanation of these constraints see books online for the pages titled: "Constraints" and "CREATE TABLE", "ALTER TABLE"
What is an index? What are the types of indexes? How many clustered indexes can be created on a table? I create a separate index on each column of a table. what are the advantages and disadvantages of this approach?
Indexes in SQL Server are similar to the indexes in books. They help SQL Server retrieve the data quicker.
Indexes are of two types. Clustered indexes and non-clustered indexes. When you craete a clustered index on a table, all the rows in the table are stored in the order of the clustered index key. So, there can be only one clustered index per table. Non-clustered indexes have their own storage separate from the table data storage. Non-clustered indexes are stored as B-tree structures (so do clustered indexes), with the leaf level nodes having the index key and it's row locater. The row located could be the RID or the Clustered index key, depending up on the absence or presence of clustered index on the table.
If you create an index on each column of a table, it improves the query performance, as the query optimizer can choose from all the existing indexes to come up with an efficient execution plan. At the same t ime, data modification operations (such as INSERT, UPDATE, DELETE) will become slow, as every time data changes in the table, all the indexes need to be updated. Another disadvantage is that, indexes need disk space, the more indexes you have, more disk space is used.
What is RAID and what are different types of RAID configurations?
RAID stands for Redundant Array of Inexpensive Disks, used to provide fault tolerance to database servers. There are six RAID levels 0 through 5 offering different levels of performance, fault tolerance. MSDN has some information about RAID levels and for detailed information, check out the RAID advisory board's homepage
What are the steps you will take to improve performance of a poor performing query?
This is a very open ended question and there could be a lot of reasons behind the poor performance of a query. But some general issues that you could talk about would be: No indexes, table scans, missing or out of date statistics, blocking, excess recompilations of stored procedures, procedures and triggers without SET NOCOUNT ON, poorly written query with unnecessarily complicated joins, too much normalization, excess usage of cursors and temporary tables.
Some of the tools/ways that help you troubleshooting performance problems are: SET SHOWPLAN_ALL ON, SET SHOWPLAN_TEXT ON, SET STATISTICS IO ON, SQL Server Profiler, Windows NT /2000 Performance monitor, Graphical execution plan in Query Analyzer.
Download the white paper on performance tuning SQL Server from Microsoft web site. Don't forget to check out sql-server-performance.com
What are the steps you will take, if you are tasked with securing an SQL Server?
Again this is another open ended question. Here are some things you could talk about: Preferring NT authentication, using server, databse and application roles to control access to the data, securing the physical database files using NTFS permissions, using an unguessable SA password, restricting physical access to the SQL Server, renaming the Administrator account on the SQL Server computer, disabling the Guest account, enabling auditing, using multiprotocol encryption, setting up SSL, setting up firewalls, isolating SQL Server from the web server etc.
Read the white paper on SQL Server security from Microsoft website. Also check out My SQL Server security best practices
What is a deadlock and what is a live lock? How will you go about resolving deadlocks?
Deadlock is a situation when two processes, each having a lock on one piece of data, attempt to acquire a lock on the other's piece. Each process would wait indefinitely for the other to release the lock, unless one of the user processes is terminated. SQL Server detects deadlocks and terminates one user's process.
A livelock is one, where a request for an exclusive lock is repeatedly denied because a series of overlapping shared locks keeps interfering. SQL Server detects the situation after four denials and refuses further shared locks. A livelock also occurs when read transactions monopolize a table or page, forcing a write transaction to wait indefinitely.
Check out SET DEADLOCK_PRIORITY and "Minimizing Deadlocks" in SQL Server books online. Also check out the article Q169960 from Microsoft knowledge base.

Oracle Interview Questions
31.Can null keys be entered in cluster index, normal index ?
Yes.

32.Can Check constraint be used for self referential integrity ? How ?
Yes. In the CHECK condition for a column of a table, we can reference some other column of the same table and thus enforce self referential integrity.

33.What are the min. extents allocated to a rollback extent ?
Two

34.What are the states of a rollback segment ? What is the difference between partly available and needs recovery ?
The various states of a rollback segment are :ONLINE, OFFLINE, PARTLY AVAILABLE, NEEDS RECOVERY and INVALID.

35.What is the difference between unique key and primary key ?
Unique key can be null; Primary key cannot be null.

36.An insert statement followed by a create table statement followed by rollback ? Will the rows be inserted ?
Yes.

37.Can you define multiple savepoints ?
Yes.

38.Can you Rollback to any savepoint ?
Yes.

40.What is the maximum no. of columns a table can have ?
256.
21.What are mutating triggers ?
A trigger giving a SELECT on the table on which the trigger is written.

22.What are constraining triggers ?
A trigger giving an Insert / Update on a table having referential integrity constraint on the triggering table.

23.Describe Oracle database's physical and logical structure ?
Physical : Data files, Redo Log files, Control file.
Logical : Tables, Views, Tablespaces, etc.

24.Can you increase the size of a tablespace ? How ?
Yes, by adding datafiles to it.

25.Can you increase the size of datafiles ? How ?
No (for Oracle 7.0)Yes (for Oracle 7.3 by using the Resize clause ----- Confirm !!).

26.What is the use of Control files ?
Contains pointers to locations of various data files, redo log files, etc.

27.What is the use of Data Dictionary ?
Used by Oracle to store information about various physical and logical Oracle structures e.g. Tables, Tablespaces, datafiles, etc

28.What are the advantages of clusters ?
Access time reduced for joins.

29.What are the disadvantages of clusters ?
The time for Insert increases.

30.Can Long/Long RAW be clustered ?
No.
11.What are the constructs of a procedure, function or a package ?
The constructs of a procedure, function or a package are : variables and constants cursors exceptions

12.Why Create or Replace and not Drop and recreate procedures ?
So that Grants are not dropped.

13.Can you pass parameters in packages ? How ?
Yes. You can pass parameters to procedures or functions in a package.

14.What are the parts of a database trigger ?
The parts of a trigger are:
A triggering event or statement
A trigger restriction
A trigger action

15.What are the various types of database triggers ?
There are 12 types of triggers, they are combination of :
Insert, Delete and Update Triggers.
Before and After Triggers.
Row and Statement Triggers.(3*2*2=12)

16.What is the advantage of a stored procedure over a database trigger ?
We have control over the firing of a stored procedure but we have no control over the firing of a trigger.

17.What is the maximum no. of statements that can be specified in a trigger statement ?
One.

18.Can views be specified in a trigger statement ?
No

19.What are the values of :new and :old in Insert/Delete/Update Triggers ?
INSERT : new = new value, old = NULL
DELETE : new = NULL, old = old value
UPDATE : new = new value, old = old value

20.What are cascading triggers? What is the maximum no of cascading triggers at a time?
When a statement in a trigger body causes another trigger to be fired, the triggers are said to be cascading. Max = 32.
1.What are the various types of Exceptions ?
User defined and Predefined Exceptions.

2.Can we define exceptions twice in same block ?
No.

3.What is the difference between a procedure and a function ?
Functions return a single variable by value whereas procedures do not return any variable by value. Rather they return multiple variables by passing variables by reference through their OUT parameter.

4.Can you have two functions with the same name in a PL/SQL block ?
Yes.

5.Can you have two stored functions with the same name ?
Yes.

6.Can you call a stored function in the constraint of a table ?
No.

7.What are the various types of parameter modes in a procedure ?
IN, OUT AND INOUT.

8.What is Over Loading and what are its restrictions ?
OverLoading means an object performing different functions depending upon the no. of parameters or the data type of the parameters passed to it.

9.Can functions be overloaded ?
Yes.

10.Can 2 functions have same name & input parameters but differ only by return datatype?
No.
What is precedence in Oracle?
It is the order in which Oracle evaluates different conditions in the same expression
What is a predicate in SQL?
Syntax that specifies a subset of rows to be returned. Predicates are specified in the WHERE clause of a SQL statement.
What is a primary key?
The column or set of columns included in the definition of a table's PRIMARY KEY constraint. A primary key's values uniquely identify the rows in a table. Only one primary key can be defined for each table.
What is a Primary Key Constraint?
This constraint is used to identify the primary key for a table. This operation requires that the primary columns are unique, and Oracle will create a unique index on the target primary key.
What is Resource Definition Framework (RDF)?
A set of rules (a sort of language) for creating descriptions of information, especially information available on the World Wide Web. RDF could be used to describe a collection of books, or artists, or a collection of web pages as in the RSS data format which uses RDF to create machine-readable summaries of web sites.
RDF is also used in XPFE applications to define the relationships between different collections of elements, for example RDF could be used to define the relationship between the data in a database and the way that data is displayed to a user.
What is a redo log?
A set of files that protect altered database data in memory that has not been written to the datafiles. The redo log can consist of two parts: the online redo log and the archived redo log.
What is a REF CURSOR? Compare strong and week ref cursor types.
A REF CURSOR is a data type. A variable created based on such a data type is generally called a cursor variable. A cursor variable can be associated with different queries at run-time. The primary advantage of using cursor variables is their capability to pass result sets between sub programs (like stored procedures, functions, packages etc.).
A strong ref cursor type definition specifies a return type, a weak definition does not.
Since Oracle 9i you can use SYS_REFCURSOR as the type for the returning REF_CURSOR.
What is referential datatype?
A variable can have either a simple or "scalar" datatype, such as NUMBER or VARCHAR2. Alternately, a variable can have a referential datatype that uses reference to a table column to derive its datatype
What is a schema?
Collection of logical structures of data, or schema objects
What is Semantic Web?
The Semantic Web is an extension of the current Web that will allow you to find, share, and combine information more easily. It relies on machine-readable information and metadata expressed in RDF.
What is a Shared pool?
Portion of the system global area that contains shared memory constructs such as shared SQL areas. A shared SQL area is required to process every unique SQL statement submitted to a database.
flush shared pool – clear all SQL statements that are in the Shared Pool Area
What is SQL trace?
The SQL Trace facility provides performance information on individual SQL statements. It generates the following statistics for each statement:
-Parse, execute, and fetch counts
-CPU and elapsed times
-Physical reads and logical reads
-Number of rows processed
-Misses on the library cache
-Username under which each parse occurred
-Each commit and rollback
You can enable the SQL Trace facility for a session or for an instance. When the SQL Trace facility is enabled, performance statistics for all SQL statements executed in a user session or in the instance are placed into trace files.
What is SQLCODE?
The function SQLCODE returns the number code of the most recent exception
What is statistics?
Statistics calculate the data distribution and storage characteristics of tables, columns, indexes, and partitions. The cost-based optimization approach uses these statistics to calculate the selectivity of predicates and to estimate the cost of each execution plan. Selectivity is the fraction of rows in a table that the SQL statement's predicate chooses. The optimizer uses the selectivity of a predicate to estimate the cost of a particular access method and to determine the optimal join order and join method.
The statistics are stored in the data dictionary and can be exported from one database and imported into another
What is a table function?
Table functions are designed to return a set of rows through PL/SQL logic but are intended to be used as a normal table or view in a SQL statement.
Example: select * from table(a_function(a_parm));
What is tkprof?
TKPROF program formats the contents of the trace file and place the output into a readable output file.
What difference is between TRANSLATE and REPLACE functions?
TRANSLATE('char','search_str','replace_str')
Replace every occurrence of search_str with replace_str
Unlike REPLACE() if replace_str is NULL the function returns NULL
What is an UNIQUE key constraint?
A data integrity constraint requiring that every value in a column or set of columns (key) be unique--that is, no two rows of a table have duplicate values in a specified column or set of columns.
What is a view?
A logical representation of another table or combination of tables
What is a hash function?
A hash function returns a value for an input, and the output is generally shorter or more compact than the input
What is an index?
Optional structure associated with tables and clusters. You can create indexes on one or more columns of a table to speed access to data on that table.
Oracle's two major index types are Bitmap indexes and B-Tree indexes. B-Tree indexes are the regular type, and bitmap indexes are a highly compressed index type that tends to be used primarily for data warehouses.
The B-tree index is the most-used type of index that Oracle provides. It provides fast lookup of rows containing a desired key value. It is not suitable if the column(s) being indexed are of low cardinality (number of distinct values). For those situations, a bitmap index is very useful, but be aware that bitmap indexes are very expensive to update when DML is performed on the indexed table.
What is an Oracle instance?
A system global area (SGA) and the Oracle background processes constitute an Oracle database instance. Every time a database is started, a system global area is allocated and Oracle background processes are started. The SGA is deallocated when the instance shuts down.
After starting an instance, Oracle associates the instance with the specified database. This is called mounting the database. The database is then ready to be opened, which makes it accessible to authorized users.
What is integrity constraint?
Declarative method of defining a rule for a column of a table. Integrity constraints enforce the business rules associated with a database and prevent the entry of invalid information into tables.
What is JDBC?
Java Database Connectivity is an API (Applications Programming Interface) that allows Java to send SQL statements to an object-relational database such as Oracle.
What are Oracle logical structures
Logical structures of an Oracle database include tablespaces, schema objects, data blocks, extents, and segments. Because the physical and logical structures are separate, the physical storage of data can be managed without affecting the access to logical storage structures
What is a materialized view
A materialized view provides indirect access to table data by storing the results of a query in a separate schema object.
What is MERGE statement in Oracle?
The MERGE statement (AKA "UPSERT") released in Oracle 9i is possibly one of the most useful ETL-enabling technologies built into the Oracle kernel. It enables us to either UPDATE or INSERT a row into a target table in one statement. You tell Oracle your rules for determining whether a target row should UPDATEd or INSERTed from the source

What is a mutating table?
A table that is currently being modified by an UPDATE, DELETE, or INSERT statement, or a table that might be updated by the effects of a DELETE CASCADE constraint.
The error is encountered when a row-level trigger accesses the same table on which it is based, while executing.
What is a nested table?
Nested table collections are an extension of the index-by tables. The main difference between the two is that nested tables can be stored in a database column
Describe the normalization.
The process of organizing data to minimize redundancy. Normalization usually involves dividing a database into tables and defining relationships between the tables. The objective is to isolate data so that additions, deletions, and modifications of a field can be made in just one table and then propagated through the rest of the database via the defined relationships.
-First Normal Form (1NF): Each field in a table contains different information. No Repeating groups.
-Second Normal Form (2NF):
Primary key can not be subdivided into separate logical entities.
Every non-key attribute is fully dependent on the key.
-Third Normal Form (3NF)
No functional dependencies on non-key fields.
What is an outer join?
An outer join does not require each record in the two joined tables to have a matching record in the other table
What is Web Ontology Language?
An OWL ontology may include descriptions of classes, along with their related properties and instances. OWL is designed for use by applications that need to process the content of information instead of just presenting information to humans. It facilitates greater machine interpretability of Web content than that supported by XML, RDF, and RDF Schema
What is Oracle package?
A schema object that groups logically related PL/SQL types, items, and subprograms. Packages offer several advantages: modularity, easier application design, information hiding, added functionality, and better performance.
What are parsing and its phases? What is soft parse?
The first two phases of the parse are Syntax Check and Semantic Analysis happen for each and every SQL statement within the database. Then Oracle database needs to check in the Shared Pool to determine if the current SQL statement being parsed has already been processed by any other sessions.
If yes, the parse operation can skip the next two functions in the process: Optimization and Row Source Generation (it is soft parse)
What is partitioning?
Partitioning is a method of splitting large tables and indexes into smaller, more manageable pieces.
What are Oracle physical structures?
Physical database structures of an Oracle database include datafiles, redo log files, and control files.
Describe general concepts of PL/SQL.
PL/SQL is Oracle's procedural extension to SQL. With PL/SQL, you can manipulate data with SQL statements, and control program flow with procedural constructs such as IF-THEN and LOOP. You can also declare constants and variables, define procedures and functions, use collections and object types, and trap run-time errors.
Applications written using any of the Oracle programmatic interfaces can call PL/SQL stored procedures and send blocks of PL/SQL code to the server for execution.
Because it runs inside the database, PL/SQL code is very efficient for data-intensive operations, and minimizes network traffic in client/server applications.
Describe PLS_INTEGER datatype.
PLS_INTEGER and BINARY_INTEGER are identical datatypes and are only available in PL/SQL. You cannot create a column in a table with either of these data types. PLS_INTEGER is a highly efficient integer 32-bit data type. You will most commonly see PLS_INETGER (and BINARY_INETGER) in PL/SQL routines as an index variable. An associative array (INDEX BY TABLE) index. Both PLS_INTEGER and BINARY_INTEGER allow whole numbers only. Decimal fractions are rounded to the nearest whole number.
What is a pragma?
Pragma is a keyword in Oracle PL/SQL that is used to provide an instruction to the compiler like PRAGMA AUTONOMOUS_TRANSACTION
Describe the package DBMS_STATS.
With the DBMS_STATS package you can view and modify optimizer statistics gathered for database objects.
The statistics to be viewed or modified can reside in the dictionary or in a table created in the user's schema for this purpose. You can also collect and manage user-defined statistics for tables and domain indexes using this package. For example, if the DELETE_COLUMN_STATS procedure is invoked on a column for which an association is defined, user-defined statistics for that column are deleted in addition to deletion of the standard statistics.
Only statistics stored in the dictionary have an impact on the cost-based optimizer. You can also use DBMS_STATS to gather statistics in parallel
Describe the package DBMS_TRACE.
The DBMS_TRACE package contains the interface to trace PL/SQL functions, procedures, and exceptions.
DBMS_TRACE provides subprograms to start and stop PL/SQL tracing in a session. Oracle collects the trace data as the program executes and writes it to database tables.
What is the DCL language?
DCL is Data Control Language statements (GRANT, COMMIT)
What is the DDL language?
DDL (Data Definition Language) statements are used to define the database structure or schema (CREATE, ALTER, TRUNCATE)
What is a dedicated server?
A database server configuration in which a server process handles requests for a single user process.
What are dispatcher processes in Oracle?
Optional background processes, present only when a shared server configuration is used. At least one dispatcher process is created for every communication protocol in use (D000, . . ., Dnnn). Each dispatcher process is responsible for routing requests from connected user processes to available shared server processes and returning the responses back to the appropriate user processes.
What is distributed transaction?
A transaction that updates data on two or more networked computer systems
distributed transaction
What is the DML language?
DML (Data Manipulation Language) statements are used for managing data within schema objects. (INSERT, MERGE, EXPLAIN PLAN)
Describe the embedded SQL and Pro*C environment.
SQL statements embedded within a program and prepared before the program is executed.
It is a method of combining the computing power of a high-level language like C/C++ and the database manipulation capabilities of SQL. It allows you to execute any SQL statement from an application program. Oracle's embedded SQL environment is called Pro*C.
A Pro*C program is compiled in two steps. First, the Pro*C precompiler recognizes the SQL statements embedded in the program, and replaces them with appropriate calls to the functions in the SQL runtime library. The output is pure C/C++ code with all the pure C/C++ portions intact. Then, a regular C/C++ compiler is used to compile the code and produces the executable.
All SQL statements need to start with EXEC SQL and end with a semicolon
What is ERP System?
Enterprise Resource Planning, a system that is used to manage all aspects of a company's operations.
ERP is a way to integrate the data and processes of an organization into one single system
Describe ETL process.
Extract, Transform, and Load (ETL) is a process in data warehousing that involves extracting data from outside sources, transforming it to fit business needs (which can include quality levels), and loading into the end target, i.e. the data warehouse.
ETL can in fact refer to a process that loads any database
ETL can also be used for the integration with legacy systems
What is EXPLANE PLAN? What information can you get using this statement?
The EXPLAIN PLAN statement displays execution plans chosen by the Oracle optimizer for SELECT, UPDATE, INSERT, and DELETE statements. A statement's execution plan is the sequence of operations Oracle performs to run the statement.
The row source tree is the core of the execution plan. It shows the following information:
-An ordering of the tables referenced by the statement
-An access method for each table mentioned in the statement
-A join method for tables affected by join operations in the statement
-Data operations like filter, sort, or aggregation
In addition to the row source tree, the plan table contains information about the following:
-Optimization, such as the cost and cardinality of each operation
-Partitioning, such as the set of accessed partitions
-Parallel execution, such as the distribution method of join inputs
The EXPLAIN PLAN results let you determine whether the optimizer selects a particular execution plan, such as, nested loops join. It also helps you to understand the optimizer decisions, such as why the optimizer chose a nested loops join instead of a hash join, and lets you understand the performance of a query.
You can use the V$SQL_PLAN to display the execution plan of a SQL statement
Describe an external tables.
External tables feature is a complement to existing SQL*Loader functionality. It allows you to access data in external sources as if it were in a table in the database.
As of Oracle Database 10g, external tables can also be written to.
To unload data, you use the ORACLE_DATAPUMP access driver. The data stream that is unloaded is in a proprietary format and contains all the column data for every row being unloaded.
An unload operation also creates a metadata stream that describes the contents of the data stream. The information in the metadata stream is required for loading the data stream. Therefore, the metadata stream is written to the datafile and placed before the data stream.
What is a function-based indexes?
Traditionally, performing a function on an indexed column in the where clause of a query guaranteed an index would not be used. Oracle 8i introduced Function Based Indexes to counter this problem. Rather than indexing a column, you index the function on that column, storing the product of the function, not the original column data.
For the optimizer to use function based indexes, the following session or system variables must be set:
QUERY_REWRITE_ENABLED=TRUE
QUERY_REWRITE_INTEGRITY=TRUSTED
Function based indexes are only visible to the Cost Based Optimizer
What is a global temporary table?
The definition of a temporary table is visible to all sessions, but the data in a temporary table is visible only to the session that inserts the data into the table. Use the CREATE GLOBAL TEMPORARY TABLE statement to create a temporary table. The ON COMMIT clause indicate if the data in the table is transaction-specific (the default) or session-specific.
What is an aggregate function? Compare with analytic function.
Aggregate function operates against a collection of values, but returns a single value. Analytic functions differ from aggregate functions in that they return multiple rows for each group.
Describe an autonomous transaction.
An autonomous transaction is an independent transaction that is initiated by another transaction, and executes without interfering with the parent transaction. When an autonomous transaction is called, the originating transaction gets suspend. Control is returned when the autonomous transaction does a COMMIT or ROLLBACK.
A procedure can be marked as autonomous by declaring it as PRAGMA AUTONOMOUS_TRANSACTION;. You may need to increase the TRANSACTIONS parameter to allow for the extra concurrent transactions.
What is a bind variable and why to use it?
A variable in a SQL statement that must be replaced with a valid value, or the address of a value, in order for the statement to successfully execute.
Used to minimize hard parses and maximize SQL reuse in the shared pool.
PL/SQL itself takes care of most of the issues to do with bind variables.
The only time you need to consciously decide to use bind variables when working with PL/SQL is when using Dynamic SQL.
Describe BULK COLLECT.
This is a form of array processing inside PL/SQL, which makes possible high-speed retrieval of data.
When data involved is very large, we can use Bulk Collect clause to fetch the data into local PL/SQL variables faster without looping through one record at a time. We can store the result set into either individual collection variables, if we are fetching certain number of columns or collection records, if we are fetching all the columns of the table.
Oracle Database achieves significant performance gains with this statement by greatly reducing the number of context switches between the PL/SQL and SQL statement execution engines.
What is a cluster?
Optional structure for storing table data. Clusters are groups of one or more tables physically stored together because they share common columns and are often used together. Because related rows are physically stored together, disk access time improves.
Describe collections and collection types.
Oracle uses collections in PL/SQL the same way other languages use arrays. Oracle provides three basic collections, each with an assortment of methods.
-Index-By Tables
-Nested Table Collections
-Varray Collections
What is a compiler?
A program to translate source code into code to be executed by a computer (object code)
What is a correlated subquery and how it my effect performance?
A subquery that uses values from the outer query. The Oracle database wants to execute the subquery once and use the results for all the evaluations in the outer query. With a correlated subquery, the database must run the subquery for each evaluation because it is based on the outer query’s data.
What is a data block?
Smallest logical unit of data storage in an Oracle database. Also called logical blocks, Oracle blocks, or pages. One data block corresponds to a specific number of bytes of physical database space on disk.
What is data dictionary?
The central set of tables and views that are used as a read-only reference about a particular database. A data dictionary stores such information as:
-The logical and physical structure of the database
-Valid users of the database
-Information about integrity constraints
-How much space is allocated for a schema object and how much of it is in use
A data dictionary is created when a database is created and is automatically updated when the structure of the database is updated.
What means a Data mining?
The computer-assisted process of digging through and analyzing enormous sets of data and then extracting the meaning of the data. Data mining tools predict behaviors and future trends, allowing businesses to make knowledge-driven decisions. Data mining tools can answer business questions that traditionally were too time consuming to resolve. They search databases for hidden patterns, finding predictive information that experts may miss because it lies outside their expectations.

What is a data type?
The attribute of a field that determines the kind of data the field can contain.
Explain concepts of a data warehouse?
A data warehouse is a relational database that is designed for query and analysis. It usually contains historical data derived from transaction data, but it can include data from other sources. It separates analysis workload from transaction workload and enables an organization to consolidate data from several sources.
In addition to a relational database, a data warehouse environment includes an extraction, transportation, transformation, and loading (ETL) solution, an online analytical processing (OLAP) engine, client analysis tools, and other applications that manage the process of gathering data and delivering it to business users.
Most data warehouses use a staging area to clean and process your operational data before
You may want to customize your warehouse's architecture for different groups within your organization. You can do this by adding data marts, which are systems designed for a particular line of business
Describe a database trigger with some details
A database trigger is a stored procedure that Oracle invokes ("fires") automatically when certain events occur, for example, when a DML operation modifies a certain table. Triggers enforce business rules, prevent incorrect values from being stored, and reduce the need to perform checking and cleanup operations in each application.
Here are some important items to remember about triggers.
-On insert triggers have no :OLD values.
-On delete triggers have no :NEW values
-Triggers do not commit transactions. If a transaction is rolled back, the data changed by the trigger is also rolled back.
-Commits, rollbacks and save points are not allowed in the trigger body. A commit/rollback affects the entire transaction, it is all or none.
-Unhandled exceptions in the trigger will cause a rollback of the entire transaction, not just the trigger.
-If more than one trigger is defined on an event, the order in which they fire is not defined. If the triggers must fire in order, you must create one trigger that executes all the actions in the required order.
-A trigger can cause other events to execute triggers.
-A trigger can not change a table that it has read from. This is the mutating table error issue.
Describe the package DBMS_PIPE.
Package DBMS_PIPE allows different sessions to communicate over named pipes. (A pipe is an area of memory used by one process to pass information to another.) You can use the procedures pack_message and send_message to pack a message into a pipe, then send it to another session in the same instance.

1. User(s) are complaining of delays when using the network. What would you do?
2. What are some of the problems associated with operating a switched LAN?
3. Name some of the ways of combining TCP/IP traffic and SNA traffic over the same link.
4. What sort of cabling is suitable for Fast Ethernet protocols?
5. What is a Class D IP address?
6. Why do I sometimes lose a server's address when using more than one server?
7. What is Firewall?
8. How do I monitor the activity of sockets?
9. How would I put my socket in non-blocking mode?
10. What are RAW sockets?
11. What is the role of TCP protocol and IP protocol.
12. What is UDP?
13. How can I make my server a daemon?
14. How should I choose a port number for my server?
15. Layers in TCP/IP



Networking, Socket Programming, Inter-Process Communication Interview Questions - 2


1. How can I be sure that a UDP message is received?
2. How to get IP header of a UDP message
3. Writing UDP/SOCK_DGRAM applications
4. How many bytes in an IPX network address?
5. What is the difference between MUTEX and Semaphore?
6. What is priority inversion?
7. Different Solutions to dining philosophers problem.
8. What is a message queue?
9. Questions on Shared Memory.
10. What is DHCP?
11. Working of ping, telnet, gopher.
12. Can I connect two computers to internet using same line ?