Oracle Sub Queries

Sub-query is the technique that lets us use the result of one query as part of another query.....
Following operators can be used in building sub queries: IN: Allows multiple values to be checked. EXIST: Checks if a value exists......
Following things need to be kept in mind when you write sub-queries: Caution should be taken with simple sub-query, especially when a normal value operator is used on the results of a sub-query, only one field must be returned....
In a simple SubQuery, the result retrieved by the inner query is fed to the outer query. The outer query takes the result as its input and processes it to produce its output....