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Asked: 2026-05-13T00:42:41+00:00

I need to perform an ON DELETE CASCADE on my table named CATEGORY, which

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I need to perform an ON DELETE CASCADE on my table named CATEGORY, which has the following columls
CAT_ID (BIGINT)
NAME (VARCHAR)
PARENT_CAT_ID (BIGINT)

PARENT_CAT_ID is a FK on CAT_ID. Obviously, the lovely SQL Server does not let me use ON DELETE CASCADE claiming circular or multiple paths to deletion.

A solution that I see often proposed is triggers. I made the following trigger:

USE [ma]
GO
/****** Object:  Trigger [dbo].[TRG_DELETE_CHILD_CATEGORIES]    Script Date: 11/23/2009 16:47:59 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER TRIGGER [dbo].[TRG_DELETE_CHILD_CATEGORIES] ON [dbo].[CATEGORY] FOR DELETE AS
SET NOCOUNT ON
/* * CASCADE DELETES TO '[Tbl B]' */
DELETE CATEGORY FROM deleted, CATEGORY WHERE deleted.CAT_ID = CATEGORY.PARENT_CAT_ID

When I manually delete a category with child categories, I get the following exception:

exception

Any idea what is wrong with my trigger?

UPDATE:
Sorry for the edit, but I have another column CATEGORY.CAT_SCH_ID, which is a FK of another table CAT_SCH.ID. This FK has a CASCADE DELETE as well, meaning that once I delete a CAT_SCH, its CATEGORies must also be deleted. So, I get this error when I define the trigger:

Cannot create INSTEAD OF DELETE or INSTEAD OF UPDATE TRIGGER ‘TRG_DEL_CATEGORY_WITH_CHILDREN’ on table ‘CATEGORY’. This is because the table has a FOREIGN KEY with cascading DELETE or UPDATE.

Any ideas?

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1 Answer

  1. Editorial Team

    The FOR DELETE trigger is raised after the original DELETE has been executed. To delete recursively, you need to write an INSTEAD OF DELETE trigger.

    The algorithm is like this:

    • Insert the PKs from deleted into a temp table

    • Find detail records of records in temp table

    • Loop until no more records are found

    DELETE records in the table by joining with temp table.

    I described recursive deletion in my blog.

    Update

    I guess you just need to drop that ON DELETE CASCADE flag from your recursive foreign key in Categories. The CASCADE flag on the foreign key from CAT_SCH should not matter.

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