大家看看这段代码可以那些地方可以优化一下?
select   table1.*,sfz.dq,A.min,T1.rate   as   ratemin,A.max,T2.rate   as   ratemax,T3.gjj_rate   as   gjj_ratemin,B.gjjmin,T4.gjj_rate   as   gjj_ratemax,B.gjjmax   from   table1  
    left   join   (   select     ygid,   min(changedate)   as   min,     max(changedate)   as   max   from     sb_rate   group   by   ygid
      )   A       on   table1.id=A.ygid  
      left   join   sb_rate   T1
      on   T1.ygid=A.ygid   and   T1.changedate=A.min
      left   join   sb_rate   T2
      on   T2.ygid=A.ygid   and   T2.changedate=A.max
      left   join   (select   ygid,min(changedate)   as   gjjmin,max(changedate)   as   gjjmax   from   gjj_rate   group   by   ygid
      )   B  
      on   table1.id=B.ygid
      left   join   gjj_rate   T3
      on   T3.ygid=B.ygid   and   T3.changedate=B.gjjmin
      left   join   gjj_rate   T4
      on   T4.ygid=B.ygid   and   T4.changedate=B.gjjmax
      left   join   sfz   on   left(id_card,6)=sfz.bm


------解决方案--------------------
--子查询试试,再合理建索引
select table1.* ,
dq=(select bm from sfz where bm=left(table1.id_card,6)),
min=(select min(changedate) from sb_rate where ygid=table1.id),
ratemin=(select rate from sb_rate where ygid=table1.id and changedate=(select min(changedate) from sb_rate where ygid=table1.id)),
max=(select max(changedate) from sb_rate where ygid=table1.id),
ratemax=(select rate from sb_rate where ygid=table1.id and changedate=(select max(changedate) from sb_rate where ygid=table1.id)),
gjj_ratemin=(select gjj_rate from gjj_rate where ygid=table1.id and changedate=(select min(changedate) from gjj_rate where ygid=table1.id)),
gjjmin=(select min(changedate) from gjj_rate where ygid=table1.id ),
gjj_ratemax=(select gjj_rate from gjj_rate where ygid=table1.id and changedate=(select max(changedate) from gjj_rate where ygid=table1.id)),
gjjmax=(select max(changedate) from gjj_rate where ygid=table1.id )
from table1