求助，自连接问题请帮忙优化sql
消息表，查询一段时间内互发消息的所有用户，请帮忙优化
select   distinct   a.SenderID

    from   (select   a.ID,   a.SenderID,   a.ReceiverID
                    from   messageTable   a
                  where   A.CreateTime   > =   '2007-02-01 '
                      and   A.CreateTime   <   '2007-02-08 '
                      )   a
  ,   (select   a.id,   a.ReceiverID,   a.SenderID
                              from   messageTable   a
                            where   A.CreateTime   > =   '2007-02-01 '
                                and   A.CreateTime   <   '2007-02-08 '
                                )   b   where   a.SenderID   =b.ReceiverID
                                                                                                    and   a.ReceiverID   =
                                                                                                            b.senderId

------解决方案--------------------
--try


select distinct a.SenderID
from messageTable as a
where exists(select 1 from messageTable where ReceiverID=a.SenderID and SenderID=a.ReceiverID)
and A.CreateTime > = '2007-02-01 ' and A.CreateTime < '2007-02-08 '
------解决方案--------------------
试试:
select
distinct a.SenderID
from
messageTable a
where
A.CreateTime between '2007-02-01 ' and '2007-02-08 ' and
exists
(
select 1 from from messageTable
where
SenderID=a.ReceiverID and ReceiverID=a.SenderID and id <> a.id
and CreateTime between '2007-02-01 ' and '2007-02-08 '
)
------解决方案--------------------
--求双方互有通信的
select
distinct senderid
from
messageTable t
where exists
(select 1 from messageTable where SenderID=t.ReceiverID and ReceiverID=t.SenderID and t.CreateTime > = '2007-02-01 ' and t.CreateTime < '2007-02-08 ')