Set - 6

Question 46 :

There is a % sign in one field of a column. What will be the query to find it?

Answer :

'' Should be used before '%'.


Question 47 :

What is ON DELETE CASCADE ?

Answer :

When ON DELETE CASCADE is specified ORACLE maintains referential integrity by automatically removing dependent foreign key values if a referenced primary or unique key value is removed.


Question 48 :

What is the fastest way of accessing a row in a table ?

Answer :

Using ROWID.CONSTRAINTS


Question 49 :

What is difference between TRUNCATE & DELETE ?

Answer :

TRUNCATE commits after deleting entire table i.e., can not be rolled back. Database triggers do not fire on TRUNCATEDELETE allows the filtered deletion. Deleted records can be rolled back or committed. Database triggers fire on DELETE.


Question 50 :

What is a transaction ?

Answer :

Transaction is logical unit between two commits and commit and rollback.