：选择具有sum（）作为子查询的查询

Question

我有一个查询需要添加一列到。我可以找到很多类似的例子，但是对于这种情况来说，没有什么比较合适。可能有无限的CategoryID，我需要添加由CategoryID分组的Sum（IsOutage）。这是一些示例数据：

这里是得到它的工作最接近我：

SELECT  c.CategoryID 
, c.Name 
, COUNT(i.IssueID) AS TotalIssues 
, AVG(DATEDIFF(MI, i.StartDate, i.ResolvedDate)) AS AvgDuration 
,(Select COUNT(h.IssueID) From dbo.hdIssues AS h Where h.CategoryID = i.CategoryID AND IsOutage = 1) AS TotalOutages 

FROM   dbo.hdCategories AS c INNER JOIN 
        dbo.hdIssues AS i ON c.CategoryID = i.CategoryID 
WHERE  (i.StatusID = 3) 
GROUP BY c.CategoryID, c.Name, TotalOutages 

我是关闭？请告知并提前感谢名单

编辑：这是一个实物模型的结果应该是什么样子：

Answer 1

如果我正确理解您的需要此查询应该给你想要的结果：

SELECT x.* , 
     y.SumIsOutage 

FROM (SELECT c.CategoryID , 
       c.Name , 
       COUNT(i.IssueID) AS TotalIssues , 
       AVG(DATEDIFF(MI, i.StartDate, i.ResolvedDate)) AS AvgDuration 
     FROM dbo.hdCategories AS c 
       INNER JOIN dbo.hdIssues AS i ON c.CategoryID = i.CategoryID 
     WHERE  (i.StatusID = 3) 
     GROUP BY c.CategoryID, c.Name) x 
     LEFT JOIN (SELECT DISTINCT i.CategoryId, 
        SUM(CONVERT(INT,i.isOutage)) OVER (PARTITION BY i.CategoryId) AS SumIsOutage 
        FROM dbo.hdIssues AS i) y 
     ON x.CategoryId = y.CategoryId 

Answer 2

可以使用条件聚集。此外，你不应该group by totaloutages

SELECT  
c.CategoryID 
, c.Name 
, COUNT(i.IssueID) AS TotalIssues 
, AVG(DATEDIFF(MI, i.StartDate, i.ResolvedDate)) AS AvgDuration 
,sum(case when IsOutage = 1 then 1 else 0 end) AS TotalOutages 
FROM dbo.hdCategories AS c INNER JOIN 
dbo.hdIssues AS i ON c.CategoryID = i.CategoryID 
WHERE i.StatusID = 3 
GROUP BY c.CategoryID, c.Name 

Answer 3

你不需要这个计数的另一个子查询。算了算，你是感兴趣的行：

COUNT(CASE WHEN i.IsOutage = 1 THEN 1 END) 

在您的查询的上下文：

SELECT  
    c.CategoryID 
, c.Name 
, COUNT(i.IssueID) AS TotalIssues 
, AVG(DATEDIFF(MI, i.StartDate, i.ResolvedDate)) AS AvgDuration 
, COUNT(CASE WHEN CONVERT(INT, i.IsOutage) = 1 THEN 1 END) AS TotalOutages 
FROM 
    dbo.hdCategories AS c 
INNER JOIN 
    dbo.hdIssues AS i 
    ON c.CategoryID = i.CategoryID 
WHERE 
    i.StatusID = 3 
GROUP BY 
    c.CategoryID 
, c.Name