如何将Row_number添加到表函数结果中

Question

我有一个从表中返回组（簇）的函数。

create function dbo.ftAllClusters() returns table as return
select distinct Cluster from Company

现在我需要为返回的每一行添加RowNumber。

Answer 1

SELECT Cluster, ROW_NUMBER() OVER(ORDER BY Cluster) AS RowNo
FROM
(
    SELECT DISTINCT Cluster
    FROM Company
) x

或者...

SELECT Cluster, ROW_NUMBER() OVER (ORDER BY Cluster) AS RowNo
FROM Company
GROUP BY Cluster

Answer 2

在SQL中有一个名为ROW_NUMBER()

的函数

修改 根据评论失去不同功能的顺序 您可以尝试SubSelet

    create function dbo.ftAllClusters() returns table as return
    Select 
       Cluster
      ,(ROW_NUMBER() OVER  (order by Cluster)) as RN
   from (
         Select 
          distinct 
          ,Cluster
          from Company ) as Comp

或者您可以尝试使用Group BY而不是Distinc（我甚至认为这有点快）

Select 
   Cluster
  ,(ROW_NUMBER() OVER  (order by Cluster)) as RN
from Company 
group by Cluster

Answer 3

这是我制定的解决方案，有更好的方法吗？

ALTER function dbo.ftAllClusters() returns table as return
With CTE(comno) as
(select distinct Cluster from  company)

select id=Row_number() over(order by comno),comno from cte