Use a HAVING clause in conjunction with a GROUP BY keyword within SELECT statements to limit a view to groups whose aggregate values meet specific criteria.

The expressions in a HAVING clause may contain constants, set functions, or an exact replica of one of the expressions in the GROUP BY expression list.

The PSQL database engine does not support the HAVING keyword without GROUP BY.

The HAVING keyword supports the use of aliases. The aliases must differ from any column names within the table.

The following example returns department names where the count of course names is greater than 5.

This same example could use aliases, in this case dn and ct, to produce the same result:

Note that COUNT(expression) counts all nonnull values for an expression across a predicate. COUNT(*) counts all values, including NULL values.

The next example returns department name that matches Accounting and has a number of courses greater than 5.

SELECT