TSQL: Return Identity ID using complex UPDATE / INSERT statements #snippet

ComplexIdentityID.sql

DECLARE @T TABLE (
    cartID INT NOT NULL
)

UPDATE
	UserCart
SET
	dateModified = GETDATE(),
	isGift = 1
OUTPUT
	INSERTED.cartID INTO @T
WHERE
	userID = 1

IF @@ROWCOUNT = 0

	INSERT
		INTO UserCart ( userID, isGift)
	OUTPUT
		INSERTED.cartID INTO @T
	VALUES (
		1,
		1
	)

SELECT cartID FROM @T