I have 3 MySQL tables (food
, apple
, and orange
).
I want to delete rows from:
apple(idapple, iduser, name)
ora
1. Login:
el@apollo:~$ mysql -u root -p
Enter password:
mysql> use your_database;
Database changed
2. Create some test tables and insert rows:
mysql> create table derp(derp1 INT);
Query OK, 0 rows affected (0.02 sec)
mysql> create table foo(foo1 INT);
Query OK, 0 rows affected (0.02 sec)
mysql> create table bar(bar1 INT);
Query OK, 0 rows affected (0.02 sec)
mysql> insert into derp values (1);
Query OK, 1 row affected (0.01 sec)
mysql> insert into foo values (1);
Query OK, 1 row affected (0.00 sec)
mysql> insert into bar values (1);
Query OK, 1 row affected (0.00 sec)
3. Make the trigger:
mysql> delimiter //
mysql> create trigger delete_foo_and_bar_when_derp_is_deleted
-> after delete on derp
-> for each row
-> begin
-> delete from foo where foo1=OLD.derp1;
-> delete from bar where bar1=OLD.derp1;
-> end//
Query OK, 0 rows affected (0.02 sec)
4. See the tables exist and all three are populated.
mysql> delimiter ;
mysql> select * from derp;
+-------+
| derp1 |
+-------+
| 1 |
+-------+
1 row in set (0.00 sec)
mysql> select * from foo;
+------+
| foo1 |
+------+
| 1 |
+------+
1 row in set (0.00 sec)
mysql> select * from bar;
+------+
| bar1 |
+------+
| 1 |
+------+
1 row in set (0.00 sec)
5. Delete from derp
mysql> delete from derp where derp1 = 1;
Query OK, 1 row affected (0.01 sec)
6. See that derp, foo, and bar are empty now:
mysql> select * from derp;
Empty set (0.00 sec)
mysql> select * from foo;
Empty set (0.00 sec)
mysql> select * from bar;
Empty set (0.00 sec)