Question

你能否帮我建立一个查询。我有一张桌子如下

Id            Info_Id                 Type
1              2                              2
2              6                              2
3              5                              3
4              8                              3
5              2                              3
6              2                              2
7              5                              2
8              8                              2
9              5                              2
10             8                              2
11             8                              2
12             5                              3
13             6                              3
14             8                              3

需要对查询进行框架处理，以便按“Info_Id”进行分组。

我需要输出如下：

Info_Id CountOfRec       Type2    Type3
2              3         2              1
5              4         2              2
6              2         1              1
8              5         3              2

我尝试如下，但我无法获得有效的输出

select  Info_Id, count(Id)as CountOfRec,
(select count(Id)from tbl_TypeInfo where Info_Id = 5 AND Type = 2) as Type2,
(select count(Id)from tbl_ TypeInfo where Info_Id = 5 AND Type = 3) as Type3
 from tbl_TypeInfo
where Info_Id = 5
group by Info_Id

输出就是这个，

Info_Id CountOfRec       Type2    Type3
5              4                              2              2

（我必须为每个“Info_id”循环以获得所需的OP，有数千条记录及其耗时）

我想从表中获得突出显示的输出。我构建的查询效率不高，可以帮助我解决这个问题。

Answer 1

您可以使用CASE表达式仅计算特定类型的行：

SELECT Info_Id,
    COUNT(*) AS CountOfRec,
    COUNT(CASE WHEN Type = 2 THEN 1 ELSE NULL END) AS Type2
    COUNT(CASE WHEN Type = 3 THEN 1 ELSE NULL END) AS Type3
FROM tbl_TypeInfo
GROUP BY Info_Id

添加WHERE Info_Id = 5以仅检索特定ID的结果。

更新：根据评论，如果您不存储ID表，则需要将IN (..)列表更改为虚拟“表”：

SELECT vt.id,
    COUNT(*) AS CountOfRec,
    COUNT(CASE WHEN Type = 2 THEN 1 ELSE NULL END) AS Type2,
    COUNT(CASE WHEN Type = 3 THEN 1 ELSE NULL END) AS Type3
FROM (
    SELECT 1 id
    UNION SELECT 2
    UNION SELECT 3
    UNION SELECT 5
    UNION SELECT 8 
  ) AS vt LEFT JOIN tbl_TypeInfo ON vt.id = tbl_TypeInfo.Info_Id
GROUP BY vt.id

Answer 2

您可以使用SQL Server的PIVOT运算符

SELECT  Info_ID
        , CountOfRec = [2] + [3]
        , Type2 = [2]
        , Type3 = [3]
FROM    (        
          SELECT  *
          FROM    (          
                    SELECT  *
                    FROM    tbl_TypeInfo
                   ) s 
          PIVOT   (COUNT(Id) FOR Type IN ([2], [3])) pvt 
        ) q

<强>测试

;WITH tbl_TypeInfo AS (
  SELECT [Id] = 1, [Info_Id] = 2, [Type] = 2
  UNION ALL SELECT 2, 6, 2
  UNION ALL SELECT 3, 5, 3
  UNION ALL SELECT 4, 8, 3
  UNION ALL SELECT 5, 2, 3
  UNION ALL SELECT 6, 2, 2
  UNION ALL SELECT 7, 5, 2
  UNION ALL SELECT 8, 8, 2
  UNION ALL SELECT 9, 5, 2
  UNION ALL SELECT 1, 8, 2
  UNION ALL SELECT 1, 8, 2
  UNION ALL SELECT 1, 5, 3
  UNION ALL SELECT 1, 6, 3
  UNION ALL SELECT 1, 8, 3
)
SELECT  Info_ID
        , CountOfRec = [2] + [3]
        , Type2 = [2]
        , Type3 = [3]
FROM    (        
          SELECT  *
          FROM    (          
                    SELECT  *
                    FROM    tbl_TypeInfo
                   ) s 
          PIVOT   (COUNT(Id) FOR Type IN ([2], [3])) pvt 
        ) q

Answer 3

这有点疯狂，但如果类型总是总是 2和3，那么可以将其作为方程式进行威胁，其中count(type2)+count(type3)=count(*)和2*count(type2)+3*count(type3)=sum(*)所以你可以像

那样

SELECT 3*c-s as Type2Count, s-2*c as Type3Count
FROM (SELECT COUNT(*) as C, SUM(Type) as S 
      FROM tbl_TypeInfo
      WHERE Info_Id = 5) SourceTable

这将是闪电般快速，然而，这是非常容易破碎!!!! 如果有的话，更改类型或添加类型，这将无效。

框架成本有效的查询

3 个答案: