Alter Table To Remove Foreign Key Or Add DELETE CASCADE (MySQL)

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Step 1 : Get the Foreign Key Name.

SHOW CREATE TABLE tableName; Note the name of Foreign key (which is mostly auto generated) output will look something like CONSTRAINT `FK4C5B93445F11A0B7` FOREIGN KEY (ID`) REFERENCES `PARENT_TABLE` (`ID`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8

Step 2: Drop the Foreign Key.

Alter table tableName drop foreign key FK4C5B93445F11A0B7 Dont worry, this will not harm your data. It will just remove the constraint. You can add it back later

Step 3: Now add the foreign key constraint back again, this time with ON DELETE CASCADE

alter table tableName add foreign key (ID) references PARENT_TABLE(ID) on DELETE CASCADE There you Go! You can run SHOW CREATE TABLE tableName; to verify on DELETE CASCADE T

Written by Tushar

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