[英]Programmatically add ON DELETE CASCADE to existing foreign key constraints on all tables
[英]Adding on Cascade Delete to existing foreign key
我的一個表中有一個外鍵,想要添加ON DELETE CASCADE,有人可以告訴我如何做到這一點請:) 謝謝
見例子:
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
)
要添加到現有表:
ALTER TABLE tbl2
ADD CONSTRAINT tbl1_id_fk
FOREIGN KEY (tbl1_id)
REFERENCES tbl1(id)
ON DELETE CASCADE;
如果使用InnoDB,請確保將FOREIGN_KEY_CHECKS參數設置為1
使用SHOW VARIABLES LIKE 'foreign_key_checks' (1=ON, 0=OFF)
的輸出驗證這一點SHOW VARIABLES LIKE 'foreign_key_checks' (1=ON, 0=OFF)
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