为什么需要 CTE 来执行以下操作

Question

以下查询错误，列名无效'rowid'

  SELECT row_number() over (partition by sales_rep order by timestamp desc) as rowid, *
  FROM dbo.you_gettheidea
where rowid = 1

然而，以下版本完美运行。我不知道为什么。

with t1 as (SELECT row_number() over (partition by sales_rep order by timestamp desc) as rowid, *
FROM dbo.you_gettheidea)

Select * from t1
Where rowid = 1

SQL 服务器 12.0.2000

编辑：看来这个问题符合following answered question

Answer 1

您不能在同一语句的 where 子句中使用列别名。它不遵守执行顺序，这就是需要 CTE 的原因。请检查 Execution order

FROM and JOIN s. The FROM clause, and subsequent JOIN s are first executed to determine the total working set of data that is being queried.

WHERE.

GROUP BY.

HAVING.

SELECT.

DISTINCT.

ORDER BY.

LIMIT / OFFSET / TOP

Answer 2

迟到的答案，但还有另一个没有 CTE 或子查询的选项...WITH TIES

Select top 1 with ties *
 From  dbo.you_gettheidea
 Order By row_number() over (partition by sales_rep order by timestamp desc)

为什么需要 CTE 来执行以下操作

Why is a CTE needed to execute the following

sql

sql-server

partition-by