Can’t Delete Jobs (Microsoft SQL Server, Error: 547)

I was creating a new job to handle weekly database maintenance and when I attempted to delete the old job, I received the following error;

TITLE: Microsoft SQL Server Management Studio
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Drop failed for Job 'Weekly_Maintenance'. (Microsoft.SqlServer.Smo)

For help, click: http://go.microsoft.com/fwlink?ProdName=Microsoft+SQL+Server&ProdVer=9.00.1399.00&EvtSrc=Microsoft.SqlServer.Management.Smo.ExceptionTemplates.FailedOperationExceptionText&EvtID=Drop+Job&LinkId=20476
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ADDITIONAL INFORMATION:
An exception occurred while executing a Transact-SQL statement or batch. (Microsoft.SqlServer.ConnectionInfo)
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The DELETE statement conflicted with the REFERENCE constraint "FK_subplan_job_id". The conflict occurred in database "msdb", table "dbo.sysmaintplan_subplans", column 'job_id'.

The statement has been terminated. (Microsoft SQL Server, Error: 547)
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If you try deleting the job from the sysmaintplan_subplans table, you also get the following error:

Msg 547, Level 16, State 0, Line 41

The DELETE statement conflicted with the REFERENCE constraint "FK_sysmaintplan_log_subplan_id". The conflict occurred in database "msdb", table "dbo.sysmaintplan_log", column 'subplan_id'.

I wanted to create a stored procedure that I could just pass a job name to and it would check each of the tables and delete all references for me. Here is what I came up with.

CREATE PROC dbo.DropJob
@JobName AS VARCHAR(200) = NULL
AS
DECLARE @msg AS VARCHAR(500);

IF @JobName IS NULL
BEGIN
SET @msg = N'A job name must be supplied for parameter @JobName.';
RAISERROR(@msg,16,1);
RETURN;
END
IF EXISTS (
SELECT subplan_id FROM msdb.dbo.sysmaintplan_log WHERE subplan_id IN
( SELECT subplan_id FROM msdb.dbo.sysmaintplan_subplans WHERE job_id IN
(SELECT job_id FROM msdb.dbo.sysjobs_view WHERE name = @JobName)))
BEGIN
DELETE FROM msdb.dbo.sysmaintplan_log WHERE subplan_id IN
( SELECT subplan_id FROM msdb.dbo.sysmaintplan_subplans WHERE job_id IN
(SELECT job_id FROM msdb.dbo.sysjobs_view WHERE name = @JobName));

DELETE FROM msdb.dbo.sysmaintplan_subplans WHERE job_id IN
(SELECT job_id FROM msdb.dbo.sysjobs_view WHERE name = @JobName);

EXEC msdb.dbo.sp_delete_job @job_name=@JobName, @delete_unused_schedule=1;
END
ELSE IF EXISTS (
SELECT subplan_id FROM msdb.dbo.sysmaintplan_subplans WHERE job_id IN
(SELECT job_id FROM msdb.dbo.sysjobs_view WHERE name = @JobName))
BEGIN
DELETE FROM msdb.dbo.sysmaintplan_subplans WHERE job_id IN
(SELECT job_id FROM msdb.dbo.sysjobs_view WHERE name = @JobName);

EXEC msdb.dbo.sp_delete_job @job_name=@JobName, @delete_unused_schedule=1;
END
ELSE
BEGIN
EXEC msdb.dbo.sp_delete_job @job_name=@JobName, @delete_unused_schedule=1;
END
GO

Now you can call the SP with the following;

USE [msdb];
EXEC dbo.DropJob @JobName = N'Shrink_AWP_Databases.Subplan_1';