mysql SQL设置外键约束ON DELETE CASCADE

第一步：删除原有的外键约束

ALTER TABLE child_table DROP FOREIGN KEY `FK_Reference_2` ;

ALTER TABLE child_table 
  ADD CONSTRAINT `FK_Reference_2`
  FOREIGN KEY (`parent_id` )
  REFERENCES parent_table (`parent_id` )
  ON DELETE CASCADE
  ON UPDATE RESTRICT;

mysql SQL设置外键约束ON DELETE CASCADE

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