Question

我对SQL Server SUM查询有疑问。

我有2张桌子：

1）EmployeesAtt（EId，EName，统计数据）->我有一些统计数据标准（0 =延迟，1 =加班，2 =正常）

   -----------------------------
   |  EId  |  EName  |  Stats  |
   -----------------------------
   |   1   |  John   |   0     |
   |---------------------------|
   |   1   |  John   |   1     |
   |---------------------------|   
   |   1   |  John   |   0     |
   |---------------------------|
   |   2   |  Lynda  |   2     |
   -----------------------------

2）AttLogs（ID，EId，延迟，加班，正常）

从EmployeesAtt表中，我想将AttLogs专用列中的EId和统计信息相加，如下所示：

   --------------------------------------------------
   |  ID   |   EId   |   late  |  overtime | Normal |
   --------------------------------------------------
   |   0   |  John   |   2     |     1     |    0   |
   |------------------------------------------------|
   |   1   |  Lynda  |   0     |     0     |    1   |
   --------------------------------------------------

这是我到目前为止所做的：

select EA.EId, EA.EName, late = case when Stats = 0 then SUM(Stats) END, 
overtime = case when Stats = 1 then SUM(Stats) END,
normal = case when Stats = 2 then SUM(Stats) END
From EmployeesAtt EA JOIN AttLogs AL ON AL.EId = EA.EId
GROUP BY EA.EId, EA.EName, EA.Stats

但结果与我上面预期的不同。

Answer 1

您需要使用条件聚合，并对CASE表达式求和/计数：

SELECT
    ea.EId,
    ea.EName,
    COUNT(CASE WHEN Stats = 0 THEN 1 END) AS late, 
    COUNT(CASE WHEN Stats = 1 THEN 1 END) AS overtime, 
    COUNT(CASE WHEN Stats = 2 THEN 1 END) AS normal
FROM EmployeesAtt ea
INNER JOIN AttLogs al
    ON al.EId = ea.EId
GROUP BY
    ea.EId,
    ea.EName;

Answer 2

在 sql服务器中最大限度地使用iif函数。

select EA.EId
    , EA.EName
    , late = sum(iif(Stats=0, 1, 0))
    , overtime = sum(iif(Stats=0, 1, 0))
    , normal = sum(iif(Stats=0, 1, 0))
From EmployeesAtt EA 
JOIN AttLogs AL ON AL.EId = EA.EId
GROUP BY EA.EId, EA.EName

在特定列中按条件求和

2 个答案: