Buy Items for User in Game

DECLARE @userId INT = (SELECT Id FROM Users
                        WHERE Username = 'Alex')
DECLARE @gameId INT = (SELECT Id FROM Games
                        WHERE Name = 'Edinburgh')
DECLARE @userGameId INT = (SELECT Id FROM UsersGames
                        WHERE UserId = @userId AND GameId = @gameId)
DECLARE @itemsSum DECIMAL(15, 2) = (
    select SUM(Price) from Items
where Name in ('Blackguard', 'Bottomless Potion of Amplification',
                'Eye of Etlich (Diablo III)', 'Gem of Efficacious Toxin',
                'Golden Gorget of Leoric', 'Hellfire Amulet'))

BEGIN TRY
BEGIN TRANSACTION
    UPDATE UsersGames
    SET Cash -= @itemsSum
    WHERE Id = @userGameId

    INSERT INTO UserGameItems
    SELECT Id, @userGameId FROM Items
    WHERE Name in ('Blackguard', 'Bottomless Potion of Amplification',
                'Eye of Etlich (Diablo III)', 'Gem of Efficacious Toxin',
                'Golden Gorget of Leoric', 'Hellfire Amulet')
COMMIT
END TRY
BEGIN CATCH
    ROLLBACK
END CATCH

SELECT u.Username, g.Name, ug.Cash, i.Name AS [Item Name]
FROM UsersGames AS ug
JOIN Games AS g ON ug.GameId = g.Id
JOIN Users AS u ON ug.UserId = u.Id
JOIN UserGameItems AS ugi ON ug.Id = ugi.UserGameId
JOIN Items AS i ON i.Id = ugi.ItemId
WHERE g.Name = 'Edinburgh'