SQL Server - Where 条件用法

Question

我想在下面的选择 sql 代码中添加条件。

select rtrim(ltrim(SUBSTRING(line,1,CHARINDEX('|',line) -1))) as drivename
      ,round(cast(rtrim(ltrim(SUBSTRING(line,CHARINDEX('|',line)+1,
      (CHARINDEX('%',line) -1)-CHARINDEX('|',line)) )) as Float)/1024,0) as 'capacity(GB)'
      ,round(cast(rtrim(ltrim(SUBSTRING(line,CHARINDEX('%',line)+1,
      (CHARINDEX('*',line) -1)-CHARINDEX('%',line)) )) as Float) /1024 ,0)as 'freespace(GB)'
from #output
where line like '[A-Z][:]%'
order by drivename

结果是;

drivename   capacity(GB)    freespace(GB) 
C:\            120                36 
D:\            100                 7

我想这样添加:'freespace(GB) > 10'

如何添加这个条件？

Answer 1

使用 CTE 或子查询:

;WITH cte as
(
select rtrim(ltrim(SUBSTRING(line,1,CHARINDEX('|',line) -1))) as drivename
      ,round(cast(rtrim(ltrim(SUBSTRING(line,CHARINDEX('|',line)+1,
      (CHARINDEX('%',line) -1)-CHARINDEX('|',line)) )) as Float)/1024,0) as 'capacity(GB)'
      ,round(cast(rtrim(ltrim(SUBSTRING(line,CHARINDEX('%',line)+1,
      (CHARINDEX('*',line) -1)-CHARINDEX('%',line)) )) as Float) /1024 ,0)as 'freespace(GB)'
from #output
where line like '[A-Z][:]%'
)
SELECT *
FROM cte
WHERE [freespace(GB)] > 10
order by drivename;

其次，这是不理解的典型例子 Logical Query Processing