I have got a foreign key in one of my tables and wanted to add ON DELETE CASCADE could anyone advise me on how to do it please :) ? thank you
See example :
CREATE TABLE tbl1(
id INT PRIMARY KEY AUTO_INCREMENT,
name INT
)
CREATE TABLE tbl2 (
id INT PRIMARY KEY AUTO_INCREMENT,
tbl1_id INT REFERENCES tbl1(id) ON DELETE CASCADE
)
To add to an existing table :
ALTER TABLE tbl2
ADD CONSTRAINT tbl1_id_fk
FOREIGN KEY (tbl1_id)
REFERENCES tbl1(id)
ON DELETE CASCADE;
If using InnoDB make sure you have FOREIGN_KEY_CHECKS parameter set to 1
Verify this with the output from SHOW VARIABLES LIKE 'foreign_key_checks' (1=ON, 0=OFF)
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