Nov 24, 2011 · here you are adding the foreign key for your "Child" table. ALTER TABLE child ADD FOREIGN KEY (P_Id) REFERENCES parent(P_Id) ON DELETE CASCADE ON UPDATE CASCADE; After that if you make a DELETE query on "Parent" table like this. DELETE FROM parent WHERE .....

usually my default is: ON DELETE RESTRICT ON UPDATE CASCADE. with some ON DELETE CASCADE for track tables (logs--not all logs--, things like that) and ON DELETE SET NULL when the master table is a 'simple attribute' for the table containing the foreign key, like a JOB table for the USER table.

If you want to change a foreign key without dropping it you can do: ALTER TABLE child_table_name WITH CHECK ADD FOREIGN KEY(child_column_name) REFERENCES parent_table_name (parent_column_name) ON DELETE CASCADE

Apr 21, 2011 · The foreign key relation can be created either through SSMS GUI or T-SQL. Rules for update/delete operations may be specified explicitly. However if nothing is specified then the default rule is No Action. The rule may be changed to any other option at any time later by recreating the FK relation.

Here are the options available for the ON DELETE clause: NO ACTION: Prevents the delete (and returns an error) if it would cause a foreign key violation. CASCADE: Propagates the delete operation to the foreign key in the child table. In other words, it deletes the related row (s) in the child table (in addition to the row in the parent table).

Jul 3, 2019 · In this article, we will review on DELETE CASCADE AND UPDATE CASCADE rules in SQL Server foreign key with different examples. DELETE CASCADE: When we create a foreign key using this option, it deletes the referencing rows in the child table when the referenced row is deleted in the parent table which has a primary key.

Aug 21, 2024 · We can use the ON DELETE CASCADE option to ensure that the delete operation does happen, and that no error is returned. This option automatically deletes related records in the child table when a record in the parent table is deleted. If we’re going to use this option, we need to define it when creating the foreign key.

Oct 15, 2015 · Deleting Specific SQL Server Records with Foreign Keys. Let's say I want to delete a record in dbo.M table WHERE id=2. We can open a new SSMS query window and run the following script.

Aug 1, 2012 · To remove the parent record we would have to have a separate delete statement for each of these child tables. Let’s also take a look a the performance differences of these two approaches.

Dec 12, 2024 · What is ON DELETE CASCADE? The "ON DELETE CASCADE" for a foreign key constraint means that if a record in the parent table (referenced table) is deleted then all related records in the child table (referencing table) will be automatically deleted.