CASCADE. It is used in conjunction with ON DELETE or ON UPDATE. It means that the child data is either deleted or updated when the parent data is deleted or updated. … It means that the child data is set to their default values when the parent data is deleted or updated.

What is Cascade update in SQL?

UPDATE CASCADE: When we create a foreign key using UPDATE CASCADE the referencing rows are updated in the child table when the referenced row is updated in the parent table which has a primary key.

What does delete on Cascade mean?

ON DELETE CASCADE constraint is used in MySQL to delete the rows from the child table automatically, when the rows from the parent table are deleted. For example when a student registers in an online learning platform, then all the details of the student are recorded with their unique number/id.