delete t
FROM News t
inner join [User] u on u.userid=t.postuserid
where datediff(hh,u.joindate,getdate())<24
FROM News t
inner join [User] u on u.userid=t.postuserid
where datediff(hh,u.joindate,getdate())<24
FROM dbo.News t
where exists(select * from dbo.User u where u.UserID = t.PostUserid
and (DATEDIFF(hh, u.JoinDate, GETDATE()) < 24) )
FROM dbo.News t INNER JOIN
dbo.User u ON u.UserID = t.PostUserid
WHERE (DATEDIFF(hh, u.JoinDate, GETDATE()) < 24)
FROM dbo.News t
inner join dbo.User u on u.userid=t.postuserid
where datediff(hh,u.joindate,getdate())<24