表里存在NULL值导致not in子查询失效的问题

表里存在NULL值导致not in子查询失效的问题

 

--这是我第一次给业务写的SQL语句，查询来数据为0，当时没考虑太多就发出去了。 后业务给我看了几条测试数据，我发现确实查询结果不对。<br>--再看语句逻辑确实没错，后经过排查是BB里有几行cust_id为NULL导致not in 查询结果失效。  www.zzzyk.com  

 

<br>--改良前的语句<br>select * from AA a with(nolock)<br>where a.status_code='04'

and a.issue_date>='2012-01-01' and a.issue_date<='2012-10-30'

and LEFT(a.manorg_code,4)='8640'

and a.cust_id not in

(

    select aa.cust_id from BB aa  with(nolock) where aa.sheet_type='Q' and aa.acttype_code in ('01','02','16','19')

)<br>

 

--改良后的语句

 

select * from AA a with(nolock)

where a.status_code='04'

and a.issue_date>='2012-01-01' and a.issue_date<='2012-10-30'

and LEFT(a.manorg_code,4)='8640'

and a.cust_id not in

(

select ISNULL(aa.cust_id,'') from BB aa with(nolock) where aa.sheet_type='Q' and aa.acttype_code in ('01','02','16','19')

)