Question { Wipro, 5216 }

How can you tune SQL statements?

Answer

SQL Statements can be tuned depending on the Database,
different DBMS provides different types of the execution
plan, Oracle provides "Explain Plain" which explains the
cost of the query. Using which we can estimate the cost and
make the necessary changes like creating indexes........

Question { 4684 }

How to find number of records in result set?

Answer

Using ResultSet MetaData class

Question { IonIdea, 9321 }

is that compulsory to have Primarykey-forignkey for joints
(outer inner,equal)

Answer

Primarykye-Foreign key relation ships are not compulsory to
join two table, but it is recommended to have.