Question

select 
   sdate,
   SUM(case when CGrp!='TOWNSHIP' and cdcode=0 and SDate between '4/1/2013' and '4/1/2013' then BillAmt end) as bill,
   sum(case  when CGrp!='TOWNSHIP' and cdcode!=0 and SDate between '4/1/2013' and '4/1/2013' then BillAmt end) as Net
from Indent
where bill != null     
group by SDate

错误消息指向bill != null

行

Answer 1

您需要使用子查询来访问选择列表中的别名。在WHERE子句中无法访问Select list bill，Net中使用的别名。

select sdate,bill,Net from
(
select sdate, 
SUM(case when CGrp!='TOWNSHIP' and cdcode=0 and SDate between '4/1/2013' and '4/1/2013' then BillAmt end)as bill, 
SUM(case when CGrp!='TOWNSHIP' and cdcode!=0 and SDate between '4/1/2013' and '4/1/2013' then BillAmt end)as Net 
from Indent  group by SDate
)z
WHERE z.bill IS NOT NULL

这是因为在查询执行的顺序中，首先执行WHERE子句，然后执行SELECT。

查询执行的一般顺序。

1 . FROM
2 . WHERE
3 . GROUP BY
4 . SELECT
5 . ORDER BY

在查询的WHERE子句中，您使用的是别名bill，但由于此别名稍后在SELECT中定义，因此会引发无效的列错误。

对于NULL比较，请使用IS / IS NOT NULL

Answer 2

something != NULL的正确语法为something IS NOT NULL

在SQL中使用大小写时的条件时无效的列名称

2 个答案: