Set - 6

Question 51 :

What are the advantages of VIEW ?

Answer :

To protect some of the columns of a table from other users.To hide complexity of a query.To hide complexity of calculations.


Question 52 :

How will you a activate/deactivate integrity constraints ?

Answer :

The integrity constraints can be enabled or disabled by ALTER TABLE ENABLE constraint/DISABLE constraint.


Question 53 :

Where the integrity constraints are stored in Data Dictionary ?

Answer :

The integrity constraints are stored in USER_CONSTRAINTS.


Question 54 :

What is the Subquery ?

Answer :

Sub query is a query whose return values are used in filtering conditions of the main query.


Question 55 :

How to access the current value and next value from a sequence ? Is it possible to access the current value in a session before accessing next value ?

Answer :

Sequence name CURRVAL, Sequence name NEXTVAL.It is not possible. Only if you access next value in the session, current value can be accessed.