Differentiate between a HAVING CLAUSE and a WHERE CLAUSE.

HAVING CLAUSE

- HAVING CLAUSE is used only with the SELECT statement.
- It is generally used in a GROUP BY clause in a query.
- If GROUP BY is not used, HAVING works like a WHERE clause.

WHERE Clause

- It is applied to each row before they become a part of the GROUP BY function in a query.

  

Where Clause	Having  Clause
WHERE clause can be used without GROUP BY clause.	HAVING is typically used in a GROUP BY clause. When GROUP BY is not used, HAVING behaves like a WHERE clause.
WHERE clause can not contain aggregate functions.	HAVING clause can contain aggregate functions.
WHERE clause can operate individual row.	HAVING clause can operate group of row.
It is more fast.	It is much slow.
WHERE clause select rows before grouping.	HAVING clause select rows after  grouping