CHECK Constraintsとしての機能 この特定のケースでは他の製品が適切ですが、MySQLはこの機能をサポートしていません。通常、トリガーは必要なことを達成するためによく使用されます。
次の例では、非常に基本的なものであり、すべての列がトリガーで検証され、50レコードを挿入しようとすると、数ミリ秒かかります。これは概念実証にすぎず、本番環境のような環境でテストを実行すると便利です。
/*Table structure for table `table_variables` */
DROP TABLE IF EXISTS `table_variables`;
CREATE TABLE `table_variables` (
`id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
`variable0` TINYINT(4) DEFAULT NULL,
`variable1` TINYINT(4) DEFAULT NULL,
`variable2` TINYINT(4) DEFAULT NULL,
`variable3` TINYINT(4) DEFAULT NULL,
`variable4` TINYINT(4) DEFAULT NULL,
`variable5` TINYINT(4) DEFAULT NULL,
`variable6` TINYINT(4) DEFAULT NULL,
`variable7` TINYINT(4) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=INNODB;
/* Trigger structure for table `table_variables` */
DELIMITER $$
/*!50003 DROP TRIGGER*//*!50032 IF EXISTS */ /*!50003 `trg_check_bi` */$$
CREATE TRIGGER `trg_check_bi` BEFORE INSERT ON `table_variables`
FOR EACH ROW
BEGIN
DECLARE msg VARCHAR(255);
DECLARE _min, _max TINYINT DEFAULT -49;
SET _max := _max * (-1);
SET @max = _max;
IF (new.`variable0` NOT BETWEEN _min AND _max) THEN
SET msg := 'Error: variable0 out of range.';
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = msg;
END IF;
IF (new.`variable1` NOT BETWEEN _min AND _max) THEN
SET msg := 'Error: variable1 out of range.';
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = msg;
END IF;
IF (new.`variable2` NOT BETWEEN _min AND _max) THEN
SET msg := 'Error: variable2 out of range.';
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = msg;
END IF;
IF (new.`variable3` NOT BETWEEN _min AND _max) THEN
SET msg := 'Error: variable3 out of range.';
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = msg;
END IF;
IF (new.`variable4` NOT BETWEEN _min AND _max) THEN
SET msg := 'Error: variable4 out of range.';
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = msg;
END IF;
IF (new.`variable5` NOT BETWEEN _min AND _max) THEN
SET msg := 'Error: variable5 out of range.';
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = msg;
END IF;
IF (new.`variable6` NOT BETWEEN _min AND _max) THEN
SET msg := 'Error: variable6 out of range.';
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = msg;
END IF;
IF (new.`variable7` NOT BETWEEN _min AND _max) THEN
SET msg := 'Error: variable7 out of range.';
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = msg;
END IF;
END $$
DELIMITER ;
INSERT `table_variables` (
`variable0`,
`variable1`,
`variable2`,
`variable3`,
`variable4`,
`variable5`,
`variable6`,
`variable7`)
VALUES
(25, 46, 6, 42, 46, -42, -6, 47),
(11, -37, 26, -3, -44, 37, -28, -4),
(14, 33, -21, 40, 19, 23, 10, 29),
(-32, 1, -47, 10, 42, 36, 5, -34),
(-38, -40, -35, -6, 27, 7, 4, -49),
(-14, 29, 41, -29, -23, 22, 31, 41),
(-34, -49, 5, 27, -27, 30, -14, -11),
(36, -30, -14, -27, -44, 10, 33, -12),
(-10, 34, -42, 29, 29, 10, 11, -21),
(6, 45, -36, 29, 7, -3, 13, 25),
(37, -35, -40, -47, 32, -42, 38, -27),
(-4, 12, 24, 36, -39, 41, -22, 12),
(-19, 14, -18, 16, -15, 27, 31, 28),
(-3, -49, 11, -44, -8, 42, -8, -21),
(-31, -44, 21, -6, -42, -47, 38, -11),
(-21, -23, -1, 17, 36, -16, -40, -3),
(-43, 40, -16, 48, 43, 22, 29, 32),
(25, -21, -32, -47, 6, 28, -28, 23),
(-45, -48, 42, 11, -22, 4, 36, 24),
(-39, -21, -34, 39, -47, -10, 46, 16),
(-10, -48, 37, -15, -37, 8, 5, -47),
(-4, -25, 32, -8, 11, 31, -25, 26),
(-40, -30, 20, 44, 12, -22, -1, 16),
(32, -33, -14, -22, -19, 20, 13, -43),
(-10, 31, 39, -44, 8, 23, 44, 3),
(32, 3, -31, -15, -32, 34, 20, 47),
(30, -42, 44, 5, 41, 43, 44, 43),
(32, -16, -31, 43, -34, 45, -14, 37),
(-15, -38, 3, -17, -46, -31, 33, 12),
(13, -22, 0, 18, 42, 9, -31, -33),
(-23, 32, -16, -27, -38, 38, -40, 30),
(26, -9, 23, -4, -38, -31, 9, -11),
(-31, 25, -24, 48, -30, 48, -10, -47),
(41, 1, 31, 4, -21, 30, -33, -9),
(8, 16, 7, 39, 25, -38, -23, -47),
(-18, 1, 13, 13, -25, -14, -43, -25),
(-47, -11, 38, -23, 15, 0, 3, -31),
(-20, 44, 37, 4, -40, 33, 39, 47),
(-29, -40, 35, -46, 6, 21, 41, -4),
(4, -16, -42, -16, -1, -6, 23, -13),
(14, -40, 5, 0, 32, 16, 34, -24),
(24, 45, 7, -49, -22, -12, -43, -29),
(32, 1, -41, 38, -28, -11, -17, -5),
(-21, -39, 13, 37, -1, 32, 17, 40),
(-1, 25, -20, -26, -22, 18, 8, 37),
(13, 4, 32, 1, -41, 36, -38, 47),
(4, 26, -29, 25, -33, 5, -24, 15),
(-1, -1, 47, -4, -15, -11, 36, -29),
(-9, -7, 42, -14, -48, 47, 39, 3),
(-31, -20, 91, 17, -89, 4, -14, 22);