Question

I have tables for a forum system. I am tring to get the following data to show on the forum page
Subject, Descripton, Last Posting Date (either post or comment), and username who made last post(either post or comment)

here are my tables

ForumSubject[
   Id,
   Subject,
   Description
 ]


ForumPost[
   id,
   Subject,
   Title
   Body,
   UserId,
   Date
 ]

ForumComment[
   id,
   PostId,
   UserId,
   Date,
   Comment

 ]

 User[
    id
    Name
  ]

Here is what i have so far

SELECT
subject.Id,
subject.Description,
subject.Subject
FROM dbo.ForumSubject subject

How now can I get the MAX Date of either a post or comment which ever is last, and the user name for the post???

Thank you!

Answer 1

You can do that :

   SELECT s.Id, s.Subject, s.Description, t2.LastDate
   FROM dbo.FormSubjet s
   INNER JOIN (
    SELECT Id, Max(Date) as LastDate
    FROM (
        SELECT Id, Date
        FROM dbo.FormPost
        UNION ALL
        SELECT Id, Date
        FROM dbo.FormComment
    ) t1
    GROUP BY t1.Id      
    ) t2 ON t2.Id = s.Id