Question

我有这样一张桌子： my_table_name

id | name | tipo
1 |你好| 0
2 |世界| 0
3 | hello3 | 0

CREATE TRIGGER  first_trigger  BEFORE INSERT ON  my_table_name  
FOR EACH ROW
BEGIN  
     IF (NEW.`tipo` <> 100 )
    THEN    
        SET NEW.tipo = 0;
    ELSE    
        SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'Error';
    END IF;
END

我想插入这个sql语句，我插入多行，第一个是错的，第二个是正确的

INSERT INTO  my_table_name(id, name, tipo) VALUES (4, 'hello1', 100), (5, 'hello5', 50);

resut table：

id | name | tipo
1 |你好| 0
2 |世界| 0
3 |你好3 | 0
5 | hello5 | 0

Answer 1

在你提出的场景中，完成你需要的东西相对简单。

当表为空时会出现问题。

mysql> DELIMITER //

mysql> DROP TABLE IF EXISTS `my_table_name`//
Query OK, 0 rows affected (0,00 sec)

mysql> CREATE TABLE IF NOT EXISTS `my_table_name` (
    ->   `id` INT UNSIGNED NOT NULL PRIMARY KEY,
    ->   `name` VARCHAR(25),
    ->   `tipo` INT UNSIGNED NOT NULL
    -> )//
Query OK, 0 rows affected (0,00 sec)

mysql> CREATE TRIGGER `first_trigger` BEFORE INSERT ON `my_table_name`
    -> FOR EACH ROW
    -> BEGIN
    ->   IF NEW.`tipo` != 100 THEN
    ->     SET NEW.`tipo` := 0;
    ->   ELSE
    ->     SET NEW.`id` := (SELECT `id` FROM `my_table_name` LIMIT 1);
    ->   END IF;
    -> END//
Query OK, 0 rows affected (0,00 sec)

mysql> DELIMITER ;

mysql> INSERT INTO `my_table_name`
    ->   (`id`, `name`, `tipo`)
    -> VALUES
    ->   (1, 'hello', 0), (2, 'world', 0), (3, 'hello3', 0);
Query OK, 3 rows affected (0,01 sec)
Records: 3  Duplicates: 0  Warnings: 0

mysql> SELECT
    ->   `id`,
    ->   `name`,
    ->   `tipo`
    -> FROM
    ->   `my_table_name`;
+----+--------+------+
| id | name   | tipo |
+----+--------+------+
|  1 | hello  |    0 |
|  2 | world  |    0 |
|  3 | hello3 |    0 |
+----+--------+------+
3 rows in set (0,00 sec)

mysql> INSERT IGNORE `my_table_name`
    ->   (`id`, `name`, `tipo`)
    -> VALUES
    ->   (4, 'hello1', 100), (5, 'hello5', 50);
Query OK, 1 row affected, 1 warning (0,00 sec)
Records: 2  Duplicates: 1  Warnings: 1

mysql> SHOW WARNINGS;
+---------+------+---------------------------------------+
| Level   | Code | Message                               |
+---------+------+---------------------------------------+
| Warning | 1062 | Duplicate entry '1' for key 'PRIMARY' |
+---------+------+---------------------------------------+
1 row in set (0,00 sec)

mysql> SELECT
    ->   `id`,
    ->   `name`,
    ->   `tipo`
    -> FROM
    ->   `my_table_name`;
+----+--------+------+
| id | name   | tipo |
+----+--------+------+
|  1 | hello  |    0 |
|  2 | world  |    0 |
|  3 | hello3 |    0 |
|  5 | hello5 |    0 |
+----+--------+------+
4 rows in set (0,00 sec)

<强>更新

另一个选项（无论表是否为空）是使用带有子句WITH CHECK OPTION的可更新视图。

mysql> DELIMITER //

mysql> DROP VIEW IF EXISTS `view_my_table_name`//
Query OK, 0 rows affected (0,00 sec)

mysql> DROP TABLE IF EXISTS `my_table_name`//
Query OK, 0 rows affected (0,00 sec)

mysql> CREATE TABLE IF NOT EXISTS `my_table_name` (
    ->   `id` INT UNSIGNED NOT NULL PRIMARY KEY,
    ->   `name` VARCHAR(25),
    ->   `tipo` INT UNSIGNED NOT NULL
    -> )//
Query OK, 0 rows affected (0,00 sec)

mysql> CREATE VIEW `view_my_table_name` AS
    ->   SELECT `id`, `name`, `tipo`
    ->   FROM `my_table_name`
    ->   WHERE `tipo` != 100
    ->   WITH LOCAL CHECK OPTION//
Query OK, 0 rows affected (0,01 sec)

mysql> CREATE TRIGGER `first_trigger` BEFORE INSERT ON `my_table_name`
    -> FOR EACH ROW
    -> BEGIN
    ->   IF NEW.`tipo` != 100 THEN
    ->     SET NEW.`tipo` := 0;
    ->   END IF;
    -> END//
Query OK, 0 rows affected (0,00 sec)

mysql> DELIMITER ;

mysql> INSERT INTO `my_table_name`
    ->   (`id`, `name`, `tipo`)
    -> VALUES
    ->   (1, 'hello', 0), (2, 'world', 0), (3, 'hello3', 0);
Query OK, 3 rows affected (0,00 sec)
Records: 3  Duplicates: 0  Warnings: 0

mysql> SELECT
    ->   `id`,
    ->   `name`,
    ->   `tipo`
    -> FROM
    ->   `my_table_name`;
+----+--------+------+
| id | name   | tipo |
+----+--------+------+
|  1 | hello  |    0 |
|  2 | world  |    0 |
|  3 | hello3 |    0 |
+----+--------+------+
3 rows in set (0,00 sec)

mysql> INSERT IGNORE `view_my_table_name`
    ->   (`id`, `name`, `tipo`)
    -> VALUES
    ->   (4, 'hello4', 100), (5, 'hello5', 50);
Query OK, 1 row affected, 1 warning (0,00 sec)
Records: 1  Duplicates: 0  Warnings: 1

mysql> SHOW WARNINGS;
+---------+------+--------------------------------------------+
| Level   | Code | Message                                    |
+---------+------+--------------------------------------------+
| Warning | 1369 | CHECK OPTION failed '_.view_my_table_name' |
+---------+------+--------------------------------------------+
1 row in set (0,00 sec)

mysql> SELECT
    ->   `id`,
    ->   `name`,
    ->   `tipo`
    -> FROM
    ->   `my_table_name`;
+----+--------+------+
| id | name   | tipo |
+----+--------+------+
|  1 | hello  |    0 |
|  2 | world  |    0 |
|  3 | hello3 |    0 |
|  5 | hello5 |    0 |
+----+--------+------+
4 rows in set (0,00 sec)

插入多个之前的mysql触发器

1 个答案: