这是一个sql语句优化的过程。使用子查询与不使用子查询的效率对比
select sum(sl0000) from xstfxps2 where
dhao00 in (
select dhao00 from xstfxps1 where trunc(ywrq00)=trunc(sysdate)
and khdm00='500000003913');
已用时间: 00: 02: 49.04
select sum(sl0000)
from xstfxps2 a,(select dhao00 from xstfxps1 where trunc(ywrq00)=trunc(sysdate)
and khdm00='500000003913') b
where a.dhao00=b.dhao00;
已用时间: 00: 00: 03.05
