MERGE Query and deleting records

Question

I have a table that looks something like:

AccountID, ItemID
1, 100
1, 200
2, 300

I have a proc that accepts a table value parameter which u

Answer 1

I can think of two obvious ways but both of them involve processing the TVP again.

The first is simply to change the DELETE condition

    WHEN NOT MATCHED BY SOURCE 
    AND target.AccountId IN(SELECT AccountId FROM @Items) THEN
        DELETE;

The second is to use a CTE to restrict the target

WITH cte as
(
SELECT ItemId, AccountId 
FROM @myTable m
WHERE EXISTS 
  (SELECT * FROM @Items i WHERE i.AccountId = m.AccountId)
)
      MERGE INTO cte as target
        USING @Items Items
           ON (Items.AccountId = target.AccountId) AND
              (Items.ItemId = target.ItemId)
        WHEN NOT MATCHED BY TARGET THEN
            INSERT (AccountId, ItemId)
            VALUES (Items.AccountId, Items.ItemId)
         WHEN NOT MATCHED BY SOURCE THEN 
            DELETE;