problem creating a simple relationship in SQL Server 2005

I am using the database diagram to simply drag one column in a table to another to associate them and then trying to save it. i have done this a million times in the past with no problems. Both of the data types are the same, uniqueidentifier.

Here is the error I get:

'Customer ' table saved successfully

'CustomerOrder ' table

- Unable to create relationship 'FK_CustomerOrder_Customer'.

The ALTER TABLE statement conflicted with the FOREIGN KEY constraint "FK_CustomerOrder_Customer". The conflict occurred in database "mydatabase", table "Custome开发者_如何转开发r", column 'CustomerID'.

Not sure how to trouble shoot this.

It means that there's a CustomerID in the CustomerOrder which can not be found in the Customer table.

Run this query inside SQL Server Management Studio separately:

SELECT *
FROM CustomerOrder co
WHERE NOT EXISTS (SELECT * FROM Customer c WHERE c.CustomerID = co.CustomerID)

and that should tell you what the "bad" Customer Order records are.

Are there customer orders with customer id's that don't exist in the customer table?