Open phpMyAdmin, and then click “SQL” tab to open its webpage, and then put in the sentences as below:

CREATE TRIGGER trigger1 AFTER INSERT ON table1
FOR EACH ROW BEGIN
INSERT INTO table2 SET t2_id = NEW.t1_id;
END;

Note: change “;” to “//” in the space behind “Delimiter”.

This trigger inserts a new record when table1 is inserted in a new record, and set the value of t2_id of the new record in table 2 to the value of new record of t1_id of table 1.

At the beginning, I used the sentence below, and the value of t2_id always 1. It works well until I

delete “and sum =1“.

A trigger example for deleting:

CREATE TRIGGER `trigger2` AFTER DELETE ON `table1`
FOR EACH ROW BEGIN
     DELETE FROM table2 WHERE t2_id = OLD.t1_id;
     UPDATE table3 SET sum = sum+1 WHERE t3_id = NEW.t1_id;
END;
 
The example below is to caculate the records of the old_table and transfer its result to new_table:

INSERT INTO new_table 
SELECT *
FROM (select ” as id, gid, count(gid) as sum from old_table group by gid) as aa 

The examples all works perfectly in my computer, but when I transferred them on the web hosting space,

I found that my account has no super privilege to use triggers and I have to delete them all.