update table_a1_2
set table_a1_2.b1=b.b1
from( select count(*) as 'b1',tradedate as 'date' from table_a1_1 a
where a.tradedate between @startdate and @enddate
and a.r<=9999
group by a.tradedate) b
where table_a1_2.tradedate=b.[date]
我只是这样的语句很多,才会出现这样的问题,为什么?