MySQL referential integrity policy setting on update and on delete

I. When there is a foreign key constraint in the table, the deletion and modification of the data in the reference table violates referential integrity and can be handled according to the following policy

1. When the two policy is set to cascade, the data in the table will be deleted when the data in the reference table is changed or deleted.

　　　　

2. When the two policy is set to no action (the default), data modification or deletion in the reference table can result in violation of integrity errors

　　　　

Error:

　　　　

MySQL referential integrity policy setting on update and on delete