Sql 将列转换为行

在SQLServer中，我编写了以下查询

SELECT 
    COUNT(DISTINCT Category) AS Categories,
    COUNT(DISTINCT [Order Number]) AS Orders,
    COUNT(DISTINCT Product) AS Products
FROM
    Associate 

输出结果如下

Categories    Orders     Products
---------------------------------
   17         13050        37

但我想要这样的结果

#Object#    |   #Count#
------------+-----------
Categories  |     17
Orders      |  13050
Products    |     37

---

有人能帮上忙吗？

您可以使用

union all

或取消打印结果：

with c as (
      select count(distinct Category) AS Categories,
             count(distinct [Order Number]) AS Orders,
             count(distinct Product) AS Products
      from Associate 
     )
select v.*
from c cross apply
     (values ('Categories', Categories),
             ('Orders', Orders),
             ('Products', Products)
     ) v(which, cnt);

这通常是最有效的选择。但是，

count（distinct）

相当昂贵，因此对表进行三次扫描可能不会对性能造成太大影响。因此：

select 'Categories' as which, count(distinct Category) as cnt
from Associate union all
select 'Orders', count(distinct [Order Number])
from Associate union all
select 'Products', count(distinct Product);

---

使用group by进行简单计数。非常感谢，两个查询都有帮助