WHAT IS DIFFERENCE BETWEEN WHERE CLAUSE AND HAVING CLAUSE ?

WHERE                                                                                                                 HAVING
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1. WHERE CLAUSE RESTRICT THE ROWS        1.HAVING CLAUSE RESTRICT THE ROWS
RETURNED BY THE SINGLE ROW FUNCT           RETURNED BY THE GROUP FUNCTIONS.
TIONS.

2.WHERE CLAUSE SHOULD APPEAR                 2.HAVING CLAUSE SHOULD APPEAR
BEFORE GROUP BY CLAUSE.                                  AFTER GROUP BY CLAUSE.