从 SQL 查询中排除子类型

Question

我有下面的 Linq 查询：

var result = (from booking in _context.Booking.AsNoTracking()
  join vendor in _context.Vendor.AsNoTracking() on booking.VendorId equals vendor.Id
  where
    booking.ClientId == userId 
  orderby booking.Id descending
  select vendor.TypeId).FirstOrDefault();

供应商可以分为移动设备或车库。 但对于我的用例，我不关心子类型。

生成的 SQL 包含带有 UNION 的子类型表。

exec sp_executesql N'SELECT TOP (1) 
    [Project3].[TypeId] AS [TypeId]
    FROM ( SELECT 
        [Extent1].[Id] AS [Id], 
        [Join1].[TypeId] AS [TypeId]
        FROM  [dbo].[Booking] AS [Extent1]
        INNER JOIN  (SELECT [UnionAll1].[VendorId] AS [VendorId], [Extent4].[TypeId] AS [TypeId]
            FROM   (SELECT 
                [Extent2].[VendorId] AS [VendorId]
                FROM [dbo].[Garage] AS [Extent2]
            UNION ALL
                SELECT 
                [Extent3].[VendorId] AS [VendorId]
                FROM [dbo].[Mobile] AS [Extent3]) AS [UnionAll1]
            INNER JOIN [dbo].[Vendor] AS [Extent4] ON [UnionAll1].[VendorId] = [Extent4].[Id] ) AS [Join1] ON [Extent1].[VendorId] = [Join1].[VendorId]
        WHERE [Extent1].[ClientId] = @p__linq__0
    )  AS [Project3]
    ORDER BY [Project3].[Id] DESC',N'@p__linq__0 uniqueidentifier',@p__linq__0='6AE9C275-7944-47B0-9B03-7B10EC88C98C'

这是浪费。 如何排除子类型不包含在 SQL 命令中？

奖金问题。 我可以让 TOP 1 在嵌套 SQL 中运行吗？ 再次。这是浪费。它首先获得完整结果，然后获得 TOP 1。