Problem 20 - Massive Shopping - Functions, Triggers and Tran

DECLARE @CurrentBalanceId INT=
    (SELECT ug.Id
    FROM Users AS u
    INNER JOIN UsersGames AS ug
    ON u.Id=ug.UserId
    INNER JOIN Games AS g
    ON ug.GameId=g.Id
    WHERE u.FirstName='Stamat' AND g.[Name]='Safflower');
DECLARE @FirstLevelItemsPrice MONEY
DECLARE @SecondLevelItemsPrice MONEY
BEGIN TRAN
    SET @FirstLevelItemsPrice = (SELECT SUM([Price])
        FROM [Items]
        WHERE [MinLevel] BETWEEN 11 AND 12)

    BEGIN TRY
        UPDATE UsersGames
        SET UsersGames.Cash-=@FirstLevelItemsPrice
        WHERE UsersGames.Id=@CurrentBalanceId

        INSERT INTO UserGameItems
        SELECT [Id] AS [ItemId], @CurrentBalanceId AS [UserGameId]
        FROM Items
        WHERE [MinLevel] BETWEEN 11 AND 12

        COMMIT
    END TRY
    BEGIN CATCH
        ROLLBACK
    END CATCH
BEGIN TRAN
    SET @SecondLevelItemsPrice = (SELECT SUM([Price])
        FROM [Items]
        WHERE [MinLevel] BETWEEN 19 AND 21)

    BEGIN TRY
        UPDATE UsersGames
        SET UsersGames.Cash-=@SecondLevelItemsPrice
        WHERE UsersGames.Id=@CurrentBalanceId

        INSERT INTO UserGameItems
        SELECT [Id] AS [ItemId], @CurrentBalanceId AS [UserGameId]
        FROM Items
        WHERE [MinLevel] BETWEEN 19 AND 21

        COMMIT
    END TRY
    BEGIN CATCH
        ROLLBACK
    END CATCH
SELECT i.[Name] AS [Item Name]
FROM UserGameItems as ugi
INNER JOIN Items as i
ON ugi.ItemId=i.Id
WHERE ugi.UserGameId=@CurrentBalanceId
ORDER BY i.[Name]