MySQL级联删除不起作用

Question

In mysql, I have two tables players and walls .

I use this to create the walls table:

CREATE TABLE walls (id int AUTO_INCREMENT, player_id int, x int, y int, PRIMARY KEY(id), FOREIGN KEY (player_id) REFERENCES players(id) ON DELETE CASCADE);

alter table walls add unique index(x, y);

The column player_id is a foreign key to the id column of the players table. I want it so that, if any rows gets deleted from the players table, then any rows from the walls table that have a foreign key to the deleted rows of the players table, should also get deleted from the walls table automatically using cascade delete. But when I do this, the rows in the walls table don't get deleted.

Anyone know whats wrong here?

Thanks

Answer 1

Confirm that your tables are actually using an engine which supports foreign keys, eg InnoDB. Older MySQLs will by default create MyISAM tables, which understand the foreign key definitions, but completely ignore them.

Simple test: show create table yourtable; . If the engine= line indicates it's a non-FK-enabled engine, there's your problem.