SQL Server-无法基于第一个新列创建其他新列

我正在选择两列，并根据列

说明

中的类别创建一个附加列

RPM

。然后，我想基于

RPM

创建一个名为

MaxRPM

的新列。如果删除第3行，该命令工作正常，但不会创建

MaxRPM

我收到以下错误：

状态1，第1行，无效列名“RPM”

SQL Server命令：

select [ID], [Date],
    max(case when Description = 'RPM' then Value end) as RPM,
    max(RPM) over (partition by [ID] order by [Date] ROWS BETWEEN 5 PRECEDING AND current row) as MaxRPM
from [DB].[Table]
where [Date] > '2019-01-01'
group by [ID], [Date]

---

为什么我在第二行创建新列时会出现此错误？任何帮助都将不胜感激。

您可以尝试以下方法-因为您不能使用别名创建其他列

with cte as
(
select [ID], [Date],
    max(case when Description = 'RPM' then Value end) as RPM
    from [DB].[Table]
where [Date] > '2019-01-01'
group by [ID], [Date]
)

select *,max(RPM) over (partition by [ID] order by [Date] ROWS BETWEEN 5 PRECEDING AND current row) as MaxRPM
from cte

---

我认为Fami命令中的第3行需要删除，否则会出现同样的错误

with cte as
(
select [ID], [Date],
    max(case when Description = 'RPM' then Value end) as RPM
from [DB].[Table]
where [Date] > '2019-01-01'
group by [ID], [Date]
)

select *,max(RPM) over (partition by [ID] order by [Date] ROWS BETWEEN 5 PRECEDING AND current row) as MaxRPM
from cte