关联查询查询多个字段的 并希望对查询结果中的某一个字段去重。

SELECT distinct (a.id),
a.sessionid,
a.mobile,
a.content,
a.pass_id,
a.extend,
j.smg_desc,
j.accountid,
a.enter_time,
a.reserved3,
a.request_time,
a.ifreport,
j.reportflag,
j.state,
j.result,
c.username,
a.deal_time,
a.reserved4,
j.mid,
j.reserved3 as bakTime
FROM cs_mt_bak a
left join cs_user c
on a.reserved1 = c.id
left join cs_resp j
on a.id = j.mid
WHERE 1 = 1
and a.reserved4=2
and to_char(a.request_time, 'YYYY-MM-DD') >=
to_char(sysdate, 'YYYY-MM-DD')
and to_char(a.request_time, 'YYYY-MM-DD') <=
to_char(sysdate, 'YYYY-MM-DD')
ORDER BY a.request_time desc, a.id
因为字段后面有些值不一样 导致去重失败 。我希望的id不重复的 后面字段可以重复