如何优化以下SQL语句

select distinct
tbd.*,
tbc.WeightExponent,tbc.BP,
tsk.SickDate,tsk.Nothing,tsk.SjtPark,tsk.XueN,tsk.SjtTime,
tpc.KUB,tpc.complication,tpc.Ksize,
tsc.Diagnosis,tsc.Pre_Cure,tsc.LocateMeth,tsc.machine1,tsc.Post,tsc.CurePart1LOrR,tsc.CureNo,
tsc.FirstDepth,tsc.FirstArea,tsc.Voltage,tsc.StrikeTimes,tsc.Feedback,tsc.tengtingzhishu,
(case trs.NoRock when 0 then '否' when 1 then '是' end) as NoRock,(case trs.ReShock when 0 then '否' when 1 then '是' end) as ReShock,(case trs.FirstShock when 0 then '否' when 1 then '是' end) as FirstShock,
trs.SWLassistcuring,trs.SWLassistcured,trs.SWLAfterAssistcure,trs.Result,
trs.syndrome,trs.compose1,trs.compose2,trs.compose3,trs.compose4,trs.metabolizecontent,trs.partcontent
from (select tm.EswlID,tb.EswlNo,tb.PName,tb.Sex,(period_diff(date_format(now(),'%Y%m'),date_format(tb.Birthday,'%Y%m')) div 12) as Age,tb.UsuallyProvince,tb.UsuallyCity,tb.Duty,DATE_FORMAT(tm.BookDate,'%Y-%m-%d') BookDate from t_basicdata tb inner join t_Main tm on tm.EswlNo=tb.EswlNo) as tbd
left join t_bodycheck tbc on tbd.EswlID=tbc.EswlID
left join t_sicknow tsk on tbd.EswlID=tsk.EswlID
left join t_piccheck tpc on tbd.EswlID=tpc.EswlID
left join t_SWLCure tsc on tbd.EswlID=tsc.EswlID
left join t_resultsurvey trs on tbd.EswlID=trs.EswlID 
order by tbd.EswlNo asc,tbd.EswlID asc


当数据达到10000条的时候，查询速度非常慢要50秒以上，请高手指教!

explain select distinct
tbd.*,
tbc.WeightExponent,tbc.BP,
tsk.SickDate,tsk.Nothing,tsk.SjtPark,tsk.XueN,tsk.SjtTime,
tpc.KUB,tpc.complication,tpc.Ksize,
tsc.Diagnosis,tsc.Pr

贴出来以供分析。

id select_type type possible_keys key key_len rows Extra
1 PRIMARY <derived2> ALL 10000 Using temporary; Using filesort
1 PRIMARY tbc ref FK_Reference_4 FK_Reference_4 5 tbd.EswlID 1
1 PRIMARY tsk ref FK_Reference_2 FK_Reference_2 5 tbd.EswlID 1
1 PRIMARY tpc ref FK_Reference_10 FK_Reference_10 5 tbd.EswlID 1
1 PRIMARY tsc ref FK_Reference_11 FK_Reference_11 4 tbd.EswlID 1
1 PRIMARY trs eq_ref PRIMARY PRIMARY 4 tbd.EswlID 1
2 DERIVED tm ALL 11427
2 DERIVED tb eq_ref PRIMARY,EswlNo PRIMARY 4 dmslt.tm.EswlNo 1 Using where