MySQL database triggers

First, only one row executes the trigger of the statement

Trigger triggers are events that trigger certain actions, including insert/delete/update, etc.

For example:

Create Trigger T_user_trig before insert
On T_user for each row
INSERT into Trigger_time values (now ());

This means that you create a trigger named T_user_trig that inserts the current time into the Trigger_time table when you perform an insert operation on table T_user.

Test it:

INSERT into T_user values (2, ' Wang ', 0, ' abcdef ', now (), ' a ');

SELECT * from Trigger_time;

II. triggers with multiple lines of execution statements

Example:

Delimiter &&
Create Trigger T_user_trig_del after delete
On T_user for each row
Begin
INSERT into trigger_time values (' 2000-01-01 10:10:00 ');
INSERT into trigger_time values (' 2001-01-01 11:11:00 ');
End
&&
Delimiter

Create a trigger named T_user_trig_del after you delete a table T_user record, two INSERT statements are executed.

SELECT * from Trigger_time;

Third, view the trigger

SELECT * from information_schema.triggers where trigger_name = ' t_user_trig ';

Iv. deleting triggers

MySQL database triggers