Question

To give you a bit of context, my database tables look like so:

User
– UserID
– Name

Message
– MessageID
– SenderUserID
– RecipientUserID

View
– ViewID
– VieweeUserID
– ViewerUserID

Using a single LINQ to SQL statement, I want get all the users that have either “Viewed” or “Messaged” a user and put them into an object like this:

Interactor
– Name (the viewer or messager)
– NumberOfMessagesSent
– NumberOfTimesViewed

I’ve tried a for ages to get what I want but every time I seem to get crazy data so I’m obviously doing something wrong… please help!

Answer 1

The name of the relationships on your model may vary (this is how LinqPad named them) but this is what I think you are trying to accomplish:

Users.Select(u => new Interactor { 
                                   Name = u.Name, 
                                   NumberOfMessagesSent = u.SenderIdMessages.Count,
                                   NumberOfTimesViewed = u.ViewerIdViews.Count 
                                 })
     .Where(i => i.NumberOfMessagesSent > 0 || i.NumberOfTimesViewed > 0);

And the generated SQL:

SELECT [t3].[Name], [t3].[value] AS [NumberOfMessagesSent], [t3].[value2] AS [NumberOfTimesViewed]
FROM (
    SELECT [t0].[Name], (
        SELECT COUNT(*)
        FROM [Message] AS [t1]
        WHERE [t1].[SenderId] = [t0].[UserId]
        ) AS [value], (
        SELECT COUNT(*)
        FROM [View] AS [t2]
        WHERE [t2].[ViewerId] = [t0].[UserId]
        ) AS [value2]
    FROM [User] AS [t0]
    ) AS [t3]
WHERE ([t3].[value] > @p0) OR ([t3].[value2] > @p1)