Oracle interview questions

1) What are the various databases you have worked with ?

Oracle , SQl server , MySql are the mostly used , but be prepared for questions on other databases if you are going to say u have worked on others  besides oracle .

2) what is sql and what is PL/SQL ?

SQL – structured query language which has a  a single line executable statement .

PL/SQL a super set of SQL enables a procedural langaue model where we can write multiple lines of SQL statements as a block.

3) how do you select the second largest salary from a table ?

using a rank function .

4) what is normalization ?

The process of decomposing tables to eliminate data redundancy is called Normalization. There are five normal forms . Google around for this .one of the irritating interview questions

5) difference between char and varchar ?

6) what is a trigger and why you need it , this can also be done bywriting the trigger code as a seperate function ?

7) what is a cursor and have you heard of REF – cursor ?

8) what is a index and when u need this . what are the different types ?

9) Difference between drop and truncate ?

10) what are the DML and DDL commands ?

11) what is a view and can we create a trigger for a view ?

12) do u know stored procedure, packages,functions ?

13) commit and rollback , savepoint ?

14) what is a package and what is UTIL ?

Package is used to group related objects like procedures , functions under one roof . UTIL is a package provided by oracle to extract or load file in oracle .

 

15) what  is decode and what is varray ?

Decode is a function which enables us to use it like IF >> THEN >> ELSE statement.

 

decode (’empname’,1000,’rich’

,101,’poor’)

 

the above code will check empname column and will return as rich if the value is 1001 and return as poor if the value is 101 .

 

16)how to catch exception errors in oracle ?

In the exception block , use raise_application_error(errcode,’err message’) for user defined exceptions .

 

These are some of the important questions when answered the interviewer believes that the resource can be trained and deployed . Happy job hunting