SQL服务器：内部连接和组由

Question

我有一个统计由电话运营商，每天处理的查询数查询

SELECT 
    [OperatorID], 
    DATEADD(day, DATEDIFF(day, 0, CreationDate), 0) AS CreationDate, 
    COUNT(*) AS EnquiryCount 
FROM 
    [Enquiries] AS e 
GROUP BY 
    [OperatorID], DATEADD(day, DATEDIFF(day, 0, CreationDate), 0) 

但是，我想给Operator表添加到该查询，使我可以检索的运营商名称

SELECT [OperatorID] 
    ,[FirstName] 
    ,[LastName] 
FROM [Operators] 

如果我内心by子句加入该组之前的2个表：

SELECT [OperatorID] 
    , DATEADD(day, DATEDIFF(day, 0, CreationDate), 0) AS CreationDate 
    , COUNT(*) AS EnquiryCount 
    , st.FullName 
FROM [Enquiries] AS e 

INNER JOIN 

(SELECT  OperatorID, FirstName + ' ' + LastName AS FullName 
FROM   dbo.Operators 
WHERE  (Role = 'Operator')) AS o ON e.OperatorID = o.OperatorID 

GROUP BY [OperatorID], DATEADD(day, DATEDIFF(day, 0, CreationDate), 0) 

我收到以下错误：

Column 'o.FullName' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause.

如何解决此问题？

Answer 1

只需添加st.FullName到Group by：

GROUP BY 
    [OperatorID], 
    DATEADD(day, DATEDIFF(day, 0, CreationDate), 0), 
    st.FullName 

Answer 2

由于OperatorID比FullName比较有特色的比你可以安全地通过子句添加FullName到组：

SELECT [OperatorID] 
    , DATEADD(day, DATEDIFF(day, 0, CreationDate), 0) AS CreationDate 
    , COUNT(*) AS EnquiryCount 
    , st.FullName 
FROM [Enquiries] AS e 

INNER JOIN 

(SELECT  OperatorID, FirstName + ' ' + LastName AS FullName 
FROM   dbo.Operators 
WHERE  (Role = 'Operator')) AS o ON e.OperatorID = o.OperatorID 

GROUP BY [OperatorID], DATEADD(day, DATEDIFF(day, 0, CreationDate), 0), st.FullName 

UPDATE正如评论指出，我建议先用最少的所需数量的列先做聚合，然后修饰结果。

SELECT si.[OperatorID], si.CreationDate, si.EnquiryCount, st.FullName 
FROM 

(
    SELECT [OperatorID] 
     , DATEADD(day, DATEDIFF(day, 0, CreationDate), 0) AS CreationDate 
     , COUNT(*) AS EnquiryCount 
    FROM [Enquiries] 
    GROUP BY [OperatorID], DATEADD(day, DATEDIFF(day, 0, CreationDate), 0) 
) AS si 

INNER JOIN 

(
    SELECT  OperatorID, FirstName + ' ' + LastName AS FullName 
    FROM   dbo.Operators 
    WHERE  (Role = 'Operator') 
) AS st 

    ON si.OperatorID = st.OperatorID 

其实我不确定，你为什么需要子查询Operators。如果没有必要，那么解决方案可以简化：

SELECT si.[OperatorID], si.CreationDate, si.EnquiryCount, 
    st.FirstName + ' ' + st.LastName AS FullName 
FROM 

(
    SELECT [OperatorID] 
     , DATEADD(day, DATEDIFF(day, 0, CreationDate), 0) AS CreationDate 
     , COUNT(*) AS EnquiryCount 
    FROM [Enquiries] 
    GROUP BY [OperatorID], DATEADD(day, DATEDIFF(day, 0, CreationDate), 0) 
) AS si 

INNER JOIN 

Operators AS st 
    ON si.OperatorID = st.OperatorID and st.Role = 'Operator' 

Answer 3

请尝试，我没有测试过！希望这将解决错误

SELECT [OperatorID], CONCAT(FirstName,LastName) AS FullName , DATEADD(day, DATEDIFF(day, 0, CreationDate), 0) AS CreationDate , COUNT(*) AS EnquiryCount , st.FullName FROM [Enquiries] AS e INNER JOIN dbo.Operators ON dbo.Operators.OperatorID = e.OperatorID AND (Role = 'Operator') GROUP BY [OperatorID], DATEADD(day, DATEDIFF(day, 0, CreationDate), 0)

Answer 4

你可以使用一个公用表表达式与ROW_NUMBER功能和COUNT(*)OVER：

WITH cte AS 
(
    SELECT e.[OperatorID] 
    , DATEADD(day, DATEDIFF(day, 0, e.CreationDate), 0) AS CreationDate 
    , o.FirstName + ' ' + o.LastName AS FullName 
    , RN = ROW_NUMBER()OVER(PARTITION BY [o.OperatorID], DATEADD(day, DATEDIFF(day, 0, e.CreationDate), 0) ORDER BY e.CreationDate DESC) 
    , EnquiryCount = COUNT(*)OVER(PARTITION BY [o.OperatorID], DATEADD(day, DATEDIFF(day, 0, e.CreationDate), 0)) 
    FROM [Enquiries] AS e 
    INNER JOIN dbo.Operators o ON e.OperatorID = o.OperatorID 
    WHERE Role = 'Operator' 
) 
SELECT * FROM cte 
WHERE RN = 1 

Answer 5

使用公共表表达式，你可以做

with cte as (
SELECT 
    [OperatorID], 
    DATEADD(day, DATEDIFF(day, 0, CreationDate), 0) AS CreationDate, 
    COUNT(*) AS EnquiryCount 
FROM 
    [Enquiries] AS e 
GROUP BY 
    [OperatorID], DATEADD(day, DATEDIFF(day, 0, CreationDate), 0) 
) 
SELECT 
cte.OperatorI,cte.CreationDate,o.FirstName + ' ' + o.LastName AS FullName 
FROM 
cte inner join dbo.Operators o 
on o.Role = 'Operator' and e.OperatorID = o.OperatorID