How do I use on delete cascade in mysql?
Here's what you'd include in your components table.
CREATE TABLE `components` ( `id` int(10) unsigned NOT NULL auto_increment, `typeId` int(10) unsigned NOT NULL, `moreInfo` VARCHAR(32), -- etc PRIMARY KEY (`id`), KEY `type` (`typeId`) CONSTRAINT `myForeignKey` FOREIGN KEY (`typeId`) REFERENCES `types` (`id`) ON DELETE CASCADE ON UPDATE CASCADE)Just remember that you need to use the InnoDB storage engine: the default MyISAM storage engine doesn't support foreign keys.
use this sql
DELETE T1, T2FROM T1INNER JOIN T2 ON T1.key = T2.keyWHERE condition
You have to define your Foreign Key constraints as ON DELETE CASCADE.
Note: You need to use InnoDB storage engine, the default MyISAM storage engine not support foreign keys relation.
CREATE TABLE `table2` (`id` int(11) NOT NULL auto_increment,`name` int(11) NOT NULL,PRIMARY KEY (`id`),KEY `ids` (`ids`)CONSTRAINT `foreign` FOREIGN KEY (`ids`) REFERENCES `table2` (`ids`) ON DELETE CASCADE ON UPDATE CASCADE)