表employees和department存在参照完整性约束,在表employees中插入记录(‘70’,‘999’)department_id为‘999’时,department表中还不存在department_id为‘999’的记录,所以违背了参照完整性约束,出现“Integrity constraint violation error”提示信息。
UPDATE employees SET department_id = 999 WHERE employee_id = 170;
-- Integrity constraint violation error
1