EXISTS Condition

An EXISTS condition tests for existence of rows in a subquery.

Description of the illustration exists_condition.gif

Table 6-11 shows the EXISTS condition.

Table 11 EXISTS Condition

Type of Condition	Operation	Example
EXISTS	TRUE if a subquery returns at least one row.	SELECT department_id FROM departments d WHERE EXISTS (SELECT * FROM employees e WHERE d.department_id = e.department_id) ORDER BY department_id;