What is the difference between no action and restrict?
What is the difference between no action and restrict?
The difference between NO ACTION and RESTRICT is that according to the standard, NO ACTION is deferred while RESTRICT acts immediately.
What is on delete restrict?
ON DELETE RESTRICT means you can’t delete a given parent row if a child row exists that references the value for that parent row.
What does on delete no action?
NO ACTION means that nothing will happen when you delete from your Subject table to the Topic table. In that case, if there is a row in Topic for a given SubjectId you cannot delete from it without breaking referential integrity, so the Delete will be rolled back.
What is on delete no action on update no action?
Specifying RESTRICT (or NO ACTION ) is the same as omitting the ON DELETE or ON UPDATE clause. NO ACTION : A keyword from standard SQL. In MySQL, equivalent to RESTRICT . The MySQL Server rejects the delete or update operation for the parent table if there is a related foreign key value in the referenced table.
What’s the difference between on delete restrict and delete no action?
The databases IBM DB2, PostgreSQL (for INITIALLY DEFERRED constraints), HSQLDB, and SQLite know the difference between ON DELETE RESTRICT and ON DELETE NO ACTION. In databases in which the two clauses are different:
What’s the difference between no action and restrict in MySQL?
RESTRICT: Rejects the delete or update operation for the parent table. Specifying RESTRICT (or NO ACTION) is the same as omitting the ON DELETE or ON UPDATE clause. NO ACTION: A keyword from standard SQL. In MySQL, equivalent to RESTRICT. The MySQL Server rejects the delete or update operation for the parent table if there is a related foreign
What is the difference between restrict and no action in PostgreSQL?
From postgresql documentation: RESTRICT prevents deletion of a referenced row. NO ACTION means that if any referencing rows still exist when the constraint is checked, an error is raised; this is the default behavior if you do not specify anything.
Which is the default action for on delete or on update?
For an ON DELETE or ON UPDATE that is not specified, the default action is always NO ACTION . As the default, an ON DELETE NO ACTION or ON UPDATE NO ACTION clause that is specified explicitly does not appear in SHOW CREATE TABLE output or in tables dumped with mysqldump .