MySQL HAVING Clause
MySQL HAVING Clause is used with GROUP BY clause. It always returns the rows where condition is TRUE.
SELECT expression1, expression2, … expression_n,
GROUP BY expression1, expression2, … expression_n
aggregate_function: It specifies any one of the aggregate function such as SUM, COUNT, MIN, MAX, or AVG.
expression1, expression2, … expression_n: It specifies the expressions that are not encapsulated within an aggregate function and must be included in the GROUP BY clause.
WHERE conditions: It is optional. It specifies the conditions for the records to be selected.
HAVING condition: It is used to restrict the groups of returned rows. It shows only those groups in result set whose conditions are TRUE.
HAVING Clause with SUM function
Consider a table “employees” table having the following data.
Here, we use the SUM function with the HAVING Clause to return the emp_name and sum of their working hours.
Execute the following query:
SELECT emp_name, SUM(working_hours) AS “Total working hours”
GROUP BY emp_name
HAVING SUM(working_hours) > 5;
Simply, it can also be used with COUNT, MIN, MAX and AVG functions.