如何从下表结构中以对话形式获取消息？

Question

这是mySql表结构（原谅系统的错误原谅）inbox_id是自动递增的主键。经过一些研究后我尝试了这个查询，但它只给出了最新消息。

SELECT a.inbox_id, msg_to, a.msg_from, a.msg_title, a.msg_body

FROM  `inbox` as a

Inner join 
(
    select max(inbox_id) as id
    from inbox as alt 
    where alt.msg_to= 12
    or alt.msg_from='12'
    GROUP BY  least(`msg_to` ,`msg_from`), greatest(`msg_to` ,  `msg_from`)
)b 
on a.inbox_id = b.id