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!

------解决方案--------------------
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。
------解决方案--------------------
把
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
做一个memory temp table试试

create table tbname(xxx,xxx,,,)engine=memory
insert into tbname
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

------解决方案--------------------
t_piccheck这个表的建表语句
------解决方案--------------------
left join 比较费资源。。
可你这要用到left　join呀，