Insert Statement For Junction Table On Many To Many Relationship Ms Sql Server 2005

Hello,

This seems like such a simple problem but I am new developer even through I have been on the administration end of things for some time. I will go into more detail about my tables and there relationships below. Anyway, I am trying to create a many-to-many relationship within ms sql server 2005. I have created both of my primary tables and also a junction table per the directions on microsoft's website all per ms's instructions as stated here...

http://msdn2.microsoft.com/en-us/library/ms178043.aspx

At then end of these instruction it states as a NOTE: The creation of a junction table in a database diagram does not insert data from the related tables into the junction table. For information about inserting data into a table, see How to: Create Insert Results Queries (Visual Database Tools).

http://msdn2.microsoft.com/en-us/library/ms189098.aspx

and these directions do not go into detail on how to do an insert on a junction table. And I cant find out how to do this anywhere on the internet... I did create a T-SQL INSERT statement in a trigger as listed below but I end up getting an error AS LISTED BELOW....

Here is how I set everything up...

PetitionSet table consists of:

PetitionSetID int auto-increment primary key
PetitionSetName varchar(50) no nulls
PetitionSetScope varchar(50) no nulls


the Petition table consists of:

PetitionID int auto-increment primary key
PetitionSetID int no nulls
PetitionName varchar(50) no nulls


the SetToPetitionJunction table consists of:
PetitionSetID int
PetitionID int

And, there is a composite key made up of both the PetitionSetID and PetitionID fields.

I have created the foreign key relationships with DEFAULT VALUES from the SetToPetitionJunction table to each column's respective corresponding column in each of the tables: PetitionSet and Petition.


The trigger is on the Petition table and it has the following code:

set ANSI_NULLS ON
set QUOTED_IDENTIFIER ON
go
-- =============================================
-- Author: Name
-- Create date:
-- Description:
-- =============================================
ALTER TRIGGER .[SetToPetitionJunctionTrigger]
ON .[dbo].[Petition]
AFTER INSERT
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;

INSERT INTO SetToPetitionJunction
(PetitionID, PetitionSetID)
SELECT Petition.PetitionID, PetitionSet.PetitionSetID
FROM Petition INNER JOIN
PetitionSet ON Petition.PetitionSetID = PetitionSet.PetitionSetID

END

I have created an asp.net 2.0 front end to insert values into the PetitionSet table and the Petition Table. And in the detailsview for the Petition table I manually insert the PetitionSetID field to the number that corresponds to an auto-generated number on the primary key of the PetitionSet table. So I am maintaining referential integrity...

The first time it works and inserts one record in the Junction table containing the PetitionSetID from the PetitionSet table and the PetitionID from the petition table.

Then when I try to add in another petition for the same petition set number just like I did the first time and then I get this error...

Violation of PRIMARY KEY constraint 'PK_SetToPetitionJunction'. Cannot insert duplicate key in object 'dbo.SetToPetitionJunction'.
The statement has been terminated.



David

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