在SQL Server列中计算相同的值

Question

我试图在列中计算相同的值，并希望它在那里返回一个计数。

| ITEM  | COUNT |
+-------+-------+
| GREEN |  1    |
| GREEN |  2    |
| GREEN |  3    |
| RED   |  1    |
| RED   |  2    |

我试过

ROW_NUMBER() OVER (ORDER BY ITEM) AS Row

但这只计算每一行1 - 1000

我将如何做到这一点？

Answer 1

尝试：

 ROW_NUMBER() OVER (PARTITION BY ITEM ORDER BY ITEM) AS Row

或

 ROW_NUMBER() OVER (PARTITION BY ITEM ORDER BY COUNT) AS Row

您可以像这样计算每个ITEM：

COUNT(*) OVER (PARTITION BY ITEM) As CountByItem

Answer 2

您需要在row_number函数中包含partition by子句。这使得row_number从每种新类型的项目重新开始。

ROW_NUMBER() OVER (PARTITION BY ITEM ORDER BY ITEM) AS Row

这会给你一个结果：

item    Row
GREEN   1
GREEN   2
GREEN   3
RED     1
RED     2

Answer 3

此代码将计算表

中的相同值

SELECT item, COUNT(*)
FROM Table
Group by item