对于联接表中计数为X或至少为X或最多为X的ID,最佳的T-SQL语法是什么?

这会让你得到你想要的。我不是说这绝对是最好的方法,但你不可能找到更好的方法。

SELECT ID
FROM   Members
INNER JOIN Comments
ON Members.MemberId = Comments.MemberId
GROUP BY ID
HAVING COUNT(*) > 100

SELECT DISTINCT m.ID
FROM Members m
WHERE (SELECT COUNT(c.CommentID)
       FROM Comments c
       WHERE c.MemberID = m.MemberID) > 100

SELECT ID
FROM Members
INNER JOIN (SELECT MemberID FROM Comments 
     GROUP BY MemberID HAVING COUNT(CommentId) > 100) 
AS CommentCount ON Members.MemberID = CommentCount.CommentID