Having clause in SQL

 Having clause:

   Ø Having clause is used to filter the group of rows returned in the GROUP BY clause.

   Ø Mainly, Aggregate functions are not allowed in the where condition so SQL prefers HAVING CLAUSE for filtering.

Syntax:

1. SELECT clm_List

   FROM Table_Name

   Where <Condition>

   [GROUP BY clm]

   HAVING <Condition>

   [ORDER BY clm];

Example:

 Table: Books

Book_Name	Order_Date	Orders
SQL	01-Dec-2000	2
DBMS	05-Sep-2000	3
PL/SQL	06-Oct-2000	4
SQL	09-Sep-2000	3
SQL	06-Oct-2001	2
DBMS	22-Jun-2001	3
PL/SQL	25-Jan-2002	3
SQL	20-jul-2002	4
DBMS	09-Nov-2003	4

  Having clause:

1. SELECT Book_name, sum(Orders)

   FROM Books

   GROUP BY Book_Name

   HAVING sum (orders) > 5

   ORDER BY orders desc;

Output:

Book_Name	Sum(Orders)
PL/SQL	7
DBMS	10
SQL	11

 

 

 

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