ASP.NET Linq To SQL 和嵌套选择

Question

我正在使用 .NET 4，我只是想知道是否有一种优化方法可以实现以下目标。

    Public Function GetUserByOpenID(ByVal claimedidentifier As String) As User Implements IUserRepository.GetUserByOpenID
        Dim user = (From u In dc.Users
                    Where u.ID = (From o In dc.OpenIDs
                                  Where o.ClaimedIdentifier = claimedidentifier
                                  Select o.UserID).FirstOrDefault
                    Select u)
        Return user
    End Function

Answer 1

假设所有用户在 OpenID 中都有匹配的 ID：

Dim user = (From u in dc.Users
            Join o in dc.OpenIDs On u.ID Equals o.UserId
            Where o.ClaimedIdentifier = claimedidentifier
            Select u).FirstOrDefault()

Answer 2

Dim user = dc.OpenIDs
    .Where(o => o.ClaimedIdentifier == claimedidentifier)
    .Select(o => o.User)

我本人偏爱 lambda...