如果 MySQL 中存在触发器，则删除触发器？

要删除触发器，请使用DROP命令。语法如下 −

DROP TRIGGER IF EXISTS yourTriggerName;

为了理解上述语法，您需要在当前数据库中有一个触发器。

要检查触发器是否存在，您可以使用以下查询。我们的数据库中有一个触发器−

mysql> show triggers;

以下是输出 −

+-------------+--------+---------------+------------------------------------------------------------------------+--------+------------------------+--------------------------------------------+---------+----------------------+----------------------+--------------------+
| Trigger     | Event   | Table        | Statement                                                              | Timing |Created                 | sql_mode                                   |  Definer                 | character_set_client | collation_connection | Database Collation |
+-------------+--------+---------------+------------------------------------------------------------------------+--------+------------------------+--------------------------------------------+---------+----------------------+----------------------+--------------------+
| CheckSalary | INSERT | employeetable | if new.EmployeeSalary < 1000 then setnew.EmployeeSalary = 10000;end if | BEFORE | 2018-12-31 17:33:29.54 |STRICT_TRANS_TABLES,NO_ENGINE_SUBSTITUTION | root@% | utf8 |utf8_general_ci | utf8mb4_0900_ai_ci |
+-------------+--------+---------------+------------------------------------------------------------------------+--------+------------------------+--------------------------------------------+---------+----------------------+----------------------+--------------------+
1 row in set (0.17 sec)

在这里，我们有一个名为’CheckSalary’的触发器在employeetable上。使用DROP命令删除触发器’CheckSalary’。查询如下 –

mysql> drop trigger if exists CheckSalary;
Query OK, 0 rows affected (0.30 sec)

使用show triggers命令检查触发器是否存在。查询如下 −

mysql> show triggers;
Empty set (0.00 sec)

现在看上面的结果，触发器不存在于数据库“test”中。我们使用 drop 将其删除。