在列上创建自定义组并计算 sql 中的另一列

Question

我正在使用 sql server，我有一个名为 Table 的表，看起来像这样。

SenderId	ReciverId	ItemCount
1	2	5
1	4	3
1	6	4
2	1	2
2	5	6
3	1	1
4	3	7
4	5	4
5	2	6
5	4	2
5	6	6
6	4	3

我想将 SenderIds 和 ReciverIds 分组。然后我想合计这些组之间的 ItemCount。分组如下。

SenderId 1 = 第一个。 SenderIds 2,3 = 第二。 SenderIds = 4,5,6 = 第三 ReciverId 1 = 第一个。 ReciverIds 2,3 = 第二。 ReciverIds = 4,5,6 = 第三

我想返回以下内容

SenderGroup	ReceiverGroup	ItemCount
First	First	0
First	Second	5
First	Third	7
Second	First	3
Second	Second	0
Second	Third	6
Third	First	0
Third	Second	13
Third	Third	15

我尝试了几个不同的查询，但都没有成功。这是我目前所拥有的一些内容。

SELECT 'First' AS SenderGroup, COUNT(ItemCount) AS ItemCount
FROM Table
WHERE SenderId IN (1)

Answer 1

要获得您期望的确切结果，您可以使用 cte 首先构建自定义组，然后创建从与 cte 连接的表中获取相关数据。

查询类似于

with dummyMap AS (
  select 1 as id, 'First' as des UNION ALL 
  select 2, 'Second' UNION ALL 
  select 3, 'Second' UNION ALL 
  select 4, 'Third' UNION ALL 
  select 5, 'Third' UNION ALL 
  select 6, 'Third' 
)
select  sndrMap.des 'SenderGroup', rcvrMap.des 'ReceiverGroup', sum(isnull(ItemCount,0)) 'ItemCount'
from dummyMap sndrMap 
cross join dummyMap rcvrMap 
left join <your-table> on ReciverId = rcvrMap.id and SenderId = sndrMap.id
group by sndrMap.des, rcvrMap.des 
order by 
    case sndrMap.des when 'First' then 1 when 'Second' then 2 else 3 end asc, 
    case rcvrMap.des when 'First' then 1 when 'Second' then 2 else 3 end asc 

here是个小提琴

Answer 2

您可以在这里使用最小/最大技巧，然后按发送者和接收者聚合并找到计数：

WITH cte AS (
    SELECT CASE WHEN SenderId < ReciverId
                THEN SenderId ELSE ReciverId END AS SenderGroup,
           CASE WHEN SenderId < ReciverId
                THEN ReciverId ELSE SenderId END AS ReceiverGroup,
           ItemCount
    FROM yourTable
)

SELECT SenderGroup, ReceiverGroup, SUM(ItemCount) AS ItemCount
FROM cte
GROUP BY SenderGroup, ReceiverGroup;

Demo