Question

what is the difference between WHERE and HAVING clause. give three points.

Answer 1

Thanks for asking this Question.

Difference between Where and Having clause:

(i) Where clause - Filter rows.

(ii) Having clause - Filter groups

(i) Where clause - Filter data before group by

(ii) Having - Filter data after group by

(i) Where clause - Cannot contain aggregate functions

(ii) Having clause - can contain aggregate functions

Example using where,Group by Having clauses together:

Select deptno,sum(salary) from emp where deptno IN(10,20) Group by deptno having sum(salary) > 10000;

Output:

Deptno                      Sum(salary)

20                                  10875

Hope it helps!

Answer 2

   A WHERE clause is used is filter records from a result.  The filter occurs before any groupings are made.

   A HAVING clause is used to filter values from a group.