Set - 10

Question 66 :

When to create indexes ?

Answer :

To be created when table is queried for less than 2% or 4% to 25% of the table rows.

Question 67 :

How can you avoid indexes ?

Answer :

TO make index access path unavailable - Use FULL hint to optimizer for full table scan - Use INDEX or AND-EQUAL hint to optimizer to use one index or set to indexes instead of another. - Use an expression in the Where Clause of the SQL.

Question 68 :

What is the result of the following SQL :

Answer :

Select 1 from dual
Select 'A' from dual;

Question 69 :

Can database trigger written on synonym of a table and if it can be then what would be the effect if original table is accessed.

Answer :

Yes, database trigger would fire.

Question 70 :

Can you alter synonym of view or view ?

Answer :