计算组内的每个条件

Question

对于每个唯一 GroupId 我想得到每个 IsGreen、IsRound、IsLoud 条件和总行数的计数。

示例数据：

-----------------------------------------------------
 id | ItemId | GroupId | IsGreen | IsRound | IsLoud
----+--------+---------+---------+---------+---------
  1 |  1001  |    1    |    0    |    1    |    1
  2 |  1002  |    1    |    1    |    1    |    0
  3 |  1003  |    2    |    0    |    0    |    0
  4 |  1004  |    2    |    1    |    0    |    1
  5 |  1005  |    2    |    0    |    0    |    0
  6 |  1006  |    3    |    0    |    0    |    0
  7 |  1007  |    3    |    0    |    0    |    0

想要的结果：

 ----------------------------------------------------------
 GroupId | TotalRows | TotalGreen | TotalRound | TotalLoud
 --------+-----------+------------+------------+-----------
    1    |     2     |     1      |     2      |     1
    2    |     3     |     1      |     0      |     1
    3    |     2     |     0      |     0      |     0

我正在使用以下代码创建 table，我遇到的问题是，如果任何组中没有任何行符合该组未出现在最终 table。完成我想做的事情的最佳方法是什么？

SELECT total.GroupId
     , total.[Count] AS TotalRows
     , IsGreen.[Count] AS TotalGreen
     , IsRound.[Count] AS TotalRound
     , IsLoud.[Count] AS TotalLoud
FROM (
    SELECT GroupId
         , count(*) AS [Count]
    FROM TestData
    GROUP BY GroupId
) TotalRows
INNER JOIN (
    SELECT GroupId
         , count(*) AS [Count]
    FROM TestData
    WHERE IsGreen = 1
    GROUP BY GroupId
) IsGreen ON IsGreen.GroupId = TotalRows.GroupId
INNER JOIN (
    SELECT GroupId
         , count(*) AS [Count]
    FROM TestData
    WHERE IsRound = 1
    GROUP BY GroupId
) IsRound ON IsRound.GroupId = TotalRows.GroupId
INNER JOIN (
    SELECT GroupId
         , count(*) AS [Count]
    FROM TestData
    WHERE IsLoud = 1
    GROUP BY GroupId
) IsLoud ON IsLoud.GroupId = TotalRows.GroupId

Answer 1

您可以使用 count 计算每个 [GroupId] 的行数，使用 sum 计算每个属性的行数。

select [GroupId]
     , count([GroupId]) as [TotalRows]
     , sum([IsGreen]) as [TotalGreen]
     , sum([IsRound]) as [TotalRound]
     , sum([IsLoud]) as [TotalLoud]
from [TestData]
group by [GroupId]

Answer 2

使用conditional Aggregate。试试这个。

SELECT GroupId,
       Count(GroupId) TotalRows,
       Count(CASE WHEN IsGreen = 1 THEN 1 END) TotalGreen,
       Count(CASE WHEN IsRound = 1 THEN 1 END) TotalRound,
       Count(CASE WHEN IsLoud = 1 THEN 1 END) TotalLoud
FROM   tablename
GROUP  BY GroupId

计算组内的每个条件

Count each condition within group

sql

sql-server

group-by

count

aggregate-functions