MySQL SQL set foreign key constraint on DELETE CASCADE

First step: Delete the original foreign KEY constraint

ALTER TABLE child_table DROP FOREIGN KEY ' fk_reference_2 ';

Step Two: Add a new foreign KEY constraint and increase the on DELETE CASCADE

ALTER TABLE child_table   ADD CONSTRAINT ' fk_reference_2 '  FOREIGN KEY (' parent_id ')  REFERENCES parent_table (' parent_id ')  On DELETE CASCADE on  UPDATE RESTRICT;

In this way, it is possible to delete the parent node automatically when the child node is deleted.

MySQL SQL set foreign key constraint on DELETE CASCADE