使用 Group By 语句时如何使用 Case

Question

我已经进行了查询，但没有给我想要的结果:

SELECT     Designation_projet, COUNT(*) AS [Nb Demande], CASE WHEN Validation = 0 THEN COUNT(*) END AS Validée, CASE WHEN Validation = 1 THEN COUNT(*) 
        END AS NonValidée, CASE WHEN Commandé = 0 THEN COUNT(*) END AS NonCommandé, 
       CASE WHEN Commandé <> 0 THEN COUNT(*) END AS Commandé,  SUM(TotalHT) AS TotalHT
FROM         V_DemandeAchat
GROUP BY Designation_projet,Commandé,Validation

请帮助我实现我的目标。

提前致谢

Answer 1

试试这个

SELECT     Designation_projet, COUNT(*) AS [Nb Demande],sum(CASE WHEN Validation = 1 THEN 1 else 0 END AS Validée,sum( CASE WHEN Validation = 1 THEN 1 else 0
        END AS NonValidée, sum(CASE WHEN NonCommandé <> 1 THEN 1 else 0 END AS NonCommandé, 
       sum(CASE WHEN Commandé <> 1 THEN 1 else 0 END AS Commandé,  SUM(TotalHT) AS TotalHT
FROM         V_DemandeAchat
GROUP BY Designation_projet

Answer 2

您可以使用条件聚合来做到这一点。这意味着 CASE 表达式是 SUM() 的参数——它是 "inside" 而不是 "outside":

SELECT Designation_projet, COUNT(*) AS [Nb Demande],
       SUM(CASE WHEN Validation = 0 THEN 1 ELSE 0 END) as Validée,
       SUM(CASE WHEN Validation = 1 THEN 1 ELSE 0 END) as NonValidée, 
       SUM(CASE WHEN Commandé = 0 THEN 1 ELSE 0 END) AS NonCommandé, 
       SUM(CASE WHEN Commandé <> 0 THEN 1 ELSE 0 END) END AS Commandé,
       SUM(TotalHT) AS TotalHT
FROM V_DemandeAchat
GROUP BY Designation_projet;

如果您想要每个 Designation_projet 一行，那么那应该是 GROUP BY 中唯一的键。

假设Validation只有两个值，你可以简化前两个聚合表达式：

SELECT Designation_projet, COUNT(*) AS [Nb Demande],
       SUM(1 - Validation) as Validée,
       SUM(Validation = 1) as NonValidée, 
       SUM(CASE WHEN Commandé = 0 THEN 1 ELSE 0 END) AS NonCommandé, 
       SUM(CASE WHEN Commandé <> 0 THEN 1 ELSE 0 END) END AS Commandé,
       SUM(TotalHT) AS TotalHT
FROM V_DemandeAchat
GROUP BY Designation_projet;

您也可以简化 Commandé 表达式。

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