The trigger would also be destroyed if we will destroy the table with which it is associated. It is called the explicit destroy of a trigger. It can be understood with the help of an example −
Example
Suppose we have a trigger named ‘trigger_before_delete_sample’ on the table named ‘Sample’. Now if we will delete this table then the above trigger associated with this table would also be deleted.
mysql> Show Triggers\G *************************** 1. row *************************** Trigger: trigger_before_delete_sample Event: DELETE Table: sample Statement: BEGIN SET @count = if (@count IS NULL, 1, (@count+1)); INSERT INTO sample_rowaffected values (@count); END Timing: BEFORE Created: 2017-11-21 12:31:58.70 sql_mode: ONLY_FULL_GROUP_BY, STRICT_TRANS_TABLES, NO_ZERO_IN_DATE, NO_ZERO_DATE, ERROR_FOR_DIVISION_BY_ZERO, NO_AUTO_CREATE_USER, NO_ENGINE_SUBSTITUTION Definer: root@localhost character_set_client: cp850 collation_connection: cp850_general_ci Database Collation: latin1_swedish_ci *************************** 2. row *************************** Trigger: before_inser_studentage Event: INSERT Table: student_age Statement: IF NEW.age < 0 THEN SET NEW.age = 0; END IF Timing: BEFORE Created: 2017-11-21 11:26:15.34 sql_mode: ONLY_FULL_GROUP_BY, STRICT_TRANS_TABLES, NO_ZERO_IN_DATE, NO_ZERO_DATE, ERROR_FOR_DIVISION_BY_ZERO, NO_AUTO_CREATE_USER, NO_ENGINE_SUBSTITUTION Definer: root@localhost character_set_client: cp850 collation_connection: cp850_general_ci Database Collation: latin1_swedish_ci 2 rows in set (0.01 sec)
The above result set shows that there are two triggers in the database among these there is a trigger that is associated with a table named ‘Sample’. Now with the help of the following statement, we will DROP the table −
mysql> DROP table sample; Query OK, 0 rows affected (0.26 sec)
Now with the help of the following statement, we can see that the trigger which was associated with a table named ‘Sample’ is also destroyed.
mysql> Show Triggers\G *************************** 1. row *************************** Trigger: before_inser_studentage Event: INSERT Table: student_age Statement: IF NEW.age < 0 THEN SET NEW.age = 0; END IF Timing: BEFORE Created: 2017-11-21 11:26:15.34 sql_mode: ONLY_FULL_GROUP_BY, STRICT_TRANS_TABLES, NO_ZERO_IN_DATE, NO_ZERO_DATE, ERROR_FOR_DIVISION_BY_ZERO, NO_AUTO_CREATE_USER, NO_ENGINE_SUBSTITUTION Definer: root@localhost character_set_client: cp850 collation_connection: cp850_general_ci Database Collation: latin1_swedish_ci 1 row in set (0.01 sec)