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Deleting child table foreignkey entire row on delete in SQL 2008

Posted on 2009-07-08
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Last Modified: 2012-05-07
Hello,

I have a table Courses which contains 1 field : CN
The other table is ADCourseMapping with 4 fields: ID, CN, SC, ADSG
I have a relationship constraint using Courses.CN as primary key to validate entries in ADCourseMapping.
I have setup the relationship to cascade on update, and cascade on delete.
However, when deleting an entry from Courses.CN, only the corresponding ADCourseMapping.CN field gets deleted. I'm actually interested in removing the whole row, as it would be no longer valid.
Is there any easy way to do this?

Please keep in mind that I have never done any SQL procedures, if accomplishing this involves using a procedure, please be as details as possible.

TiA!
Georges
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Question by:cvservices
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5 Comments
 
LVL 40

Expert Comment

by:mrjoltcola
ID: 24807270
Sounds like the ON DELETE is executing a SET NULL or SET DEFAULT rather than CASCADE. Can you show your DDL?

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Author Comment

by:cvservices
ID: 24807321
well .. at least from where I'm looking at it, it doesn't sound like it, but maybe there's something I'm missing. Here's the DDL.
USE [UserNameStore]
GO
 
/****** Object:  Table [dbo].[ADCourseMapping]    Script Date: 07/08/2009 12:29:00 ******/
SET ANSI_NULLS ON
GO
 
SET QUOTED_IDENTIFIER ON
GO
 
SET ANSI_PADDING ON
GO
 
CREATE TABLE [dbo].[ADCourseMapping](
	[ID] [int] IDENTITY(1,1) NOT NULL,
	[CN] [varchar](6) NOT NULL,
	[SC] [int] NOT NULL,
	[ADSG] [varchar](50) NOT NULL
) ON [PRIMARY]
 
GO
 
SET ANSI_PADDING OFF
GO
 
ALTER TABLE [dbo].[ADCourseMapping]  WITH CHECK ADD  CONSTRAINT [FK_ADCourseMapping_Courses] FOREIGN KEY([CN])
REFERENCES [dbo].[Courses] ([CN])
ON UPDATE CASCADE
ON DELETE CASCADE
GO
 
ALTER TABLE [dbo].[ADCourseMapping] CHECK CONSTRAINT [FK_ADCourseMapping_Courses]
GO
 
ALTER TABLE [dbo].[ADCourseMapping]  WITH CHECK ADD  CONSTRAINT [FK_ADCourseMapping_SchoolMapping] FOREIGN KEY([SC])
REFERENCES [dbo].[SchoolMapping] ([SC])
ON UPDATE CASCADE
ON DELETE CASCADE
GO
 
ALTER TABLE [dbo].[ADCourseMapping] CHECK CONSTRAINT [FK_ADCourseMapping_SchoolMapping]
GO
 
 
=============================================
USE [UserNameStore]
GO
 
/****** Object:  Table [dbo].[Courses]    Script Date: 07/08/2009 12:29:08 ******/
SET ANSI_NULLS ON
GO
 
SET QUOTED_IDENTIFIER ON
GO
 
SET ANSI_PADDING ON
GO
 
CREATE TABLE [dbo].[Courses](
	[CN] [varchar](6) NOT NULL,
 CONSTRAINT [PK_Courses_1] PRIMARY KEY CLUSTERED 
(
	[CN] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]
 
GO
 
SET ANSI_PADDING OFF
GO

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Accepted Solution

by:
mrjoltcola earned 500 total points
ID: 24807431
I ran your DDL in my local SQL 2005 and did test inserts and deletes and the child records are deleted as I expected.

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LVL 1

Author Comment

by:cvservices
ID: 24807482
That's very interesting. On mine here's an example record in Courses:
CN
5874

An example record in ADCourseMapping
ID   CN      SC      ADSG
1    5874    103    103-Business

I delete the 5874 record from Course, and I end up with the following on the corresponding ADCourseMapping record:
ID    CN     SC     ADSG
1                103   103-Business

Funny thing is, though this field has a not-null constraint, when it cascades the deletion of that particular field, the table seems ok with a NULL value. Of course, the field doesn't say "NULL" , so it may not actually be NULL as far as the table constraint is concerned.
0
 
LVL 1

Author Comment

by:cvservices
ID: 24807516
Ok ... you know , never mind, this is all my fault, and you were absolutely correct. What I did to test the constraint was actually delete the value of the CN, but never deleted the row, and that's why it reflected only the field deletion in the child table. I just retried it, and deleted the whole row, and the corresponding child table row got deleted as well.

Oh well.. I'll blame this on being an SQL noob ;-)

Thanks for pointing me in the right direction though! the points are yours.
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