The Having clause specifies conditions for groups of rows (for example, display only the departments that have salaries totaling more than $200,000). This clause is valid only if you have already defined a Group By clause.
Grammar
HAVING expr1rel_operatorexpr2
where:
expr1 | expr2
can be column names, constant values, or expressions. These expressions do not have to match a column expression in the Select clause. See SQL Expressions for details regarding SQL expressions.
rel_operator
is the relational operator that links the two expressions.
Example
The following example returns only the departments that have salaries totaling more than $200,000:
SELECT dept_id, sum(salary) FROM emp GROUP BY dept_id HAVING sum(salary) > 200000
