[英]Programmatically add ON DELETE CASCADE to existing foreign key constraints on all tables
[英]Adding on Cascade Delete to existing foreign key
我的一个表中有一个外键,想要添加ON DELETE CASCADE,有人可以告诉我如何做到这一点请:) 谢谢
见例子:
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
)
要添加到现有表:
ALTER TABLE tbl2
ADD CONSTRAINT tbl1_id_fk
FOREIGN KEY (tbl1_id)
REFERENCES tbl1(id)
ON DELETE CASCADE;
如果使用InnoDB,请确保将FOREIGN_KEY_CHECKS参数设置为1
使用SHOW VARIABLES LIKE 'foreign_key_checks' (1=ON, 0=OFF)
的输出验证这一点SHOW VARIABLES LIKE 'foreign_key_checks' (1=ON, 0=OFF)
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