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I'm creating a 'polls' plugin for my website, and for this I have 2x tables (shown below).

What I'm trying to achieve is that by delete a 'poll' from the dd_polls table, any linked foreign keys on the dd_poll_options table are also deleted.

Both tables create just fine, but my expectation as mentioned above is not happening.

Am I using foreign keys in the correct way, and if so, how can my code be fixed? Thanks.

CREATE TABLE dd_polls (
    ID smallint(3) NOT NULL AUTO_INCREMENT,
    poll_created_by smallint(3) DEFAULT "0",
    poll_created_date datetime DEFAULT "0000-00-00 00:00:00" NOT NULL,
    poll_last_edited_by smallint(3) DEFAULT "0",
    poll_last_edited_date datetime DEFAULT "0000-00-00 00:00:00" NOT NULL,
    poll_title varchar(128) COLLATE latin1_general_ci,
    poll_start_date date DEFAULT "0000-00-00" NOT NULL,
    poll_expiry_date date DEFAULT "0000-00-00" NOT NULL,
    poll_closed tinyint(1) NOT NULL,
    poll_allow_recasting tinyint(1) NOT NULL,
    poll_show_votes tinyint(1) NOT NULL,
    UNIQUE (ID)
)

CREATE TABLE dd_poll_options (
    ID smallint(3) NOT NULL AUTO_INCREMENT,
    option_text text(255) COLLATE latin1_general_ci,
    option_order smallint(2) DEFAULT "0",
    poll_id smallint(3) NOT NULL,
    FOREIGN KEY (poll_id) REFERENCES dd_polls (ID)
        ON DELETE CASCADE,
    UNIQUE (ID)
)
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2 回答 2

1

Just a wild guess, but I think you need to use the InnoDB engine for this to work. I bet you are using MyISAM.

Here is another question with the same symptoms: on-delete-cascade-not-working-in-mysql

And isn't the correct syntax 

CONSTRAINT FOREIGN KEY (poll_id) REFERENCES dd_polls(ID) ON DELETE CASCADE,

?

于 2013-10-16T15:29:02.557 回答
-1 
ALTER TABLE `dd_polls` ADD FOREIGN KEY ( `poll_id`, `id` ) 
REFERENCES `dd_poll_options` ( `poll_id`, `id`) 
ON DELETE RESTRICT ON UPDATE RESTRICT ;
于 2013-10-16T15:39:19.940 回答