请教SQL语句的含义，多谢啦。

[已到而立之年]

update sfc_proutingdres set baseQTYN=a.v
from 
( 
select baseQTYN as v from sfc_operationres where operationid='1000000109'
) a 
where sfc_proutingdres.PRoutingDId in (select sfc_proutingdres.PRoutingDId from  sfc_proutingdres join  sfc_proutingdetail on sfc_proutingdres.PRoutingDId=sfc_proutingdetail.PRoutingDId where operationid='1000000109')

这个SQL语句是什么意思？请大神指点，谢谢啦。

[Neo_whl]

一条更新语句，

update sfc_proutingdres set baseQTYN=a.v   --set 赋值语句 将后面查询中间结果看成表a,将a表中的字段v 赋值给sfc_proutingdres中的baseQTYN  where语句描述的是将sfc_proutingdres.PRoutingDId满足什么条件的记录才执行更新
from 
( 
      select baseQTYN as v from sfc_operationres where operationid='1000000109'
) a   --表别名
where sfc_proutingdres.PRoutingDId in   --更新条件 
(select sfc_proutingdres.PRoutingDId from  sfc_proutingdres join  sfc_proutingdetail on sfc_proutingdres.PRoutingDId=sfc_proutingdetail.PRoutingDId where operationid='1000000109')--in（）是一个相同属性值的集合，由两张表通过join联结，联结字段是on后面的表达式，where进行删选符合条件的记录

[houyajin]

; with t as (
select sfc_proutingdres.PRoutingDId 
from  sfc_proutingdres join  sfc_proutingdetail
on sfc_proutingdres.PRoutingDId=sfc_proutingdetail.PRoutingDId 
where operationid='1000000109')  --- 要更新数据的条件之后
update sfc_proutingdres set baseQTYN=a.v
from ( 
select baseQTYN as v from sfc_operationres where operationid='1000000109' ) a  -- 被更新数据要取 字段
where sfc_proutingdres.PRoutingDId in (select  t.sfc_proutingdres from t 

这个语句的主要用处是想要更新sfc_proutingdres 的baseQTYN这个字段，但是这个字段的取值是这个表中 operationid='1000000109' 的值，所以才会有临时表的数据，不过他没有关联这个里面的值，所以'1000000109' 对应值是多个的话， sfc_proutingdres 的baseQTYN这个字段值会是operationid='1000000109'的baseQTYN值。 条件是sfc_proutingdres.PRoutingDId在临时表中的数据，也就是你最后的那个where条件。

[已到而立之年]

多谢二位的帮助，其实还是没看懂。再慢慢学吧，非常感谢。