What is a correlated sub query?
A correlated is a query in where the inner query is executed for each record returned
by the outer query.
For Example the query:
select * from emp a
where exists (select 1 from dept b
where a.deptno = b.deptno);
Will execute the sub query for each record returned from the first query (table emp).
If the employee is assigned a deptno then only that record will be displayed.
What are the Oracle Cursor Attributes ?
There are four attributes in Oracle cursor namely:
%ISOPEN
%FOUND
%NOTFOUND
%ROWCOUNT
Atrribute usage:
%ISOPEN – Returned Values TRUE or FALSE.
Returns TRUE if the cursor is open.
Retruns FALSE if cursor is not open.
%FOUND – Returned Values TRUE or FALSE.
Returns TRUE if the cursor returned values.
Retruns FALSE if cursor does not return values.
%NOTFOUND – Returned Values TRUE or FALSE.
Returns FALSE if the cursor returned values.
Retruns TRUE if cursor does not return values.
%ROWCOUNT – Returns a number.
This attribute will retrun the number of records fetched by the cursor.
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