SQL服务器中的事务有Delete语句

Question

This is my task: write a script that includes two SQL statements coded as a transaction to delete the row with a customer ID of 8 from the Customers table. To do this, you must first delete all addresses for that customer from the Addresses table.

If these statements execute successfully, commit the changes. Otherwise, roll back the changes.

My problem is that I am getting an error that looks like this:

Msg 547, Level 16, State 0, Line 9
The DELETE statement conflicted with the REFERENCE constraint "FK__Orders__Customer__35BCFE0A". The conflict occurred in database "MyGuitarShop", table "dbo.Orders", column 'CustomerID'.

My code:

BEGIN TRAN;

DELETE FROM Addresses
WHERE CustomerID = 8;

DELETE FROM Customers
WHERE CustomerID = 8;

IF @@ROWCOUNT > 1
BEGIN
    ROLLBACK TRAN
    PRINT 'did not delete'
END
ELSE
BEGIN
    COMMIT TRAN;
END

Thank you!

Answer 1

As long as Customers is referencing any Table on your Database then you can not delete it. As per your REFERENCE constraint error message CustomerID = 8 have some order on table "dbo.Orders", column 'CustomerID' is referenced to Customers, so that`s why CustomerID=8 not deleting.

First you need to delete order from dbo.Orders Table for CustormerID=8 or use

ON DELETE CASCADE 

in the foreign key constraint definition.

Answer 2

You're trying to delete a row when another row relies on it. This is what is known as referential integrity. It's there to prevent orphaned rows.

You'll need to delete any rows that relies on Customer ID 8 elsewhere.

In this immediate case, it is:-

DELETE FROM Orders WHERE CustomerID = 8

But in your shoes, I'd probably comment as to why you're doing that, or even speak to whoever set you the task to ask if this is acceptable.