Correlated sub queries as you all know are used for row-by-row processing. Here each sub query is executed once for every row of the outer query. The oracle server performs a correlated subquery when the subquery references a column from a table referred to in the parent statement.
The general for of a correlated subquery is:
select column1, column2, . . . . . . .
from table1 outer
where [column1] operator (select column1, column2,
from table2 where expr1= outer.expr2);
To read more about Sub queries please refer our previous post
Now will see how to use correlated update and delete statements