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Is on delete cascade a trigger?
If either the Person or the Exam are deleted, you’d want the associated Exam_Score record(s) to also be deleted. This is not possible using ON DELETE CASCADE in MS SQL Server, thus the need for triggers.
How do I use cascade delete in SQL?
To add “Cascade delete” to an existing foreign key in SQL Server Management Studio: First, select your Foreign Key, and open it’s “DROP and Create To..” in a new Query window. And hit the “Execute” button to run this query. The SQL in that article lists all FKs which reference a particular table.
How do I delete on Cascade in MySQL?
ON DELETE CASCADE clause in MySQL is used to automatically remove the matching records from the child table when we delete the rows from the parent table. It is a kind of referential action related to the foreign key.
How do I use delete cascade in Oracle?
A foreign key with cascade delete means that if a record in the parent table is deleted, then the corresponding records in the child table will automatically be deleted. This is called a cascade delete in Oracle.
Can you use SQL cascade on delete or use triggers?
If either the Person or the Exam are deleted, you’d want the associated Exam_Score record(s) to also be deleted. This is not possible using ON DELETE CASCADE in MS SQL Server, thus the need for triggers. (Apologies to Mehrdad who tried to explain this to me but I completely missed his point.) Share Follow edited Sep 25 ’09 at 10:52
Can a cascade delete be cascaded to more than one table?
No, MS SQL Server doesn’t allow the deletion of a Primary Key or Unique Constraint to be cascaded to more than one table. Try setting it up and you get an error message. Cascade delete only works from 1 dimension table to 1 fact table. It doesn’t work from 1 dimension table to many fact tables.
How to solve on delete cascade cycles on MS SQL?
Same for t_link, which is an ON DELETE SET NULL promoted to CASCADE if both id_parent and id_child are NULL (i.e. deleted/non-existent): Of course, that is probably less efficient than having hand-crafted constraints, but it’s good enough (so far) for my use-case and simplifies the SQL generator code a lot.
How to create cascade paths in MS SQL?
Introducing FOREIGN KEY constraint ‘fk_t_link_child’ on table ‘t_link’ may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints.