如何合并汇总查询？

Question

我有一个查询

SELECT
    CntApp = COUNT(app.ApplicationID)
    ,r.RegionName
    ,d.DistrictName 
FROM dim.Application app
    JOIN dim.Geography g ON (app.ApplicationID  = g.GeographyID)   
       AND (app.CountryId = g.CountryId)
    JOIN dim.Region r   ON r.RegionID = g.RegionID  
    JOIN dim.District d ON d.DistrictId = g.DistrictID
    JOIN dim.ZIPcode z  ON g.ZIPcodeID = z.ZIPcodeID         
GROUP BY
    r.RegionName
    ,d.DistrictName

和

SELECT
    CntCon = COUNT(c.ContractID)
    ,r.RegionName
    ,d.DistrictName
FROM dim.Contract c  
    JOIN dim.Geography g ON (c.ContractID = g.GeographyID)   
       AND (c.CountryId = g.CountryId)
    JOIN dim.Region r   ON r.RegionID = g.RegionID  
    JOIN dim.District d ON d.DistrictId = g.DistrictID
    JOIN dim.ZIPcode z  ON g.ZIPcodeID = z.ZIPcodeID         
GROUP BY
    r.RegionName
    ,d.DistrictName

我想将其合并到一个表中，因此该分组依据仍然有效。 我想要得到的结果：

CntApp | CntCon | RegionName | DistrictName
31       24       Pardubicky   Pardubice
21       16       Pardubicky   Chrudim
...

我已经尝试了UNION ALL，但是却得到了这样的东西：

CntApp | CntCon | RegionName | DistrictName
    NULL     24       Pardubicky   Pardubice
    21       NULL     Pardubicky   Pardubice
    26       NULL     Pardubicky   Chrudim
    ...

Answer 1

您需要join 2个子查询。 这样，您将按预期并排获得两个查询的列。

这应该工作：

SELECT iq1.CntApp , iq2.CntCon, iq1.iq1.RegionName,iq1.DistrictName 
FROM
(
SELECT
    CntApp = COUNT(app.ApplicationID)
    ,r.RegionName
    ,d.DistrictName 
FROM dim.Application app
    JOIN dim.Geography g ON (app.ApplicationID  = g.GeographyID)   
       AND (app.CountryId = g.CountryId)
    JOIN dim.Region r   ON r.RegionID = g.RegionID  
    JOIN dim.District d ON d.DistrictId = g.DistrictID
    JOIN dim.ZIPcode z  ON g.ZIPcodeID = z.ZIPcodeID         
GROUP BY
    r.RegionName
    ,d.DistrictName
) iq1
inner join
(
SELECT
    CntCon = COUNT(c.ContractID)
    ,r.RegionName
    ,d.DistrictName
FROM dim.Contract c  
    JOIN dim.Geography g ON (c.ContractID = g.GeographyID)   
       AND (c.CountryId = g.CountryId)
    JOIN dim.Region r   ON r.RegionID = g.RegionID  
    JOIN dim.District d ON d.DistrictId = g.DistrictID
    JOIN dim.ZIPcode z  ON g.ZIPcodeID = z.ZIPcodeID         
GROUP BY
    r.RegionName
    ,d.DistrictName
) iq2
on
iq1.RegionName = iq2.iq1.RegionName 
and 
iq1.DistrictName = iq2.DistrictName 

Answer 2

UNION ALL将逐列合并结果。 您需要引入伪造的列并再次聚合（或像其他解决方案一样加入）：

SELECT SUM(CntApp) CntApp, SUM(CntCon) CntCon, RegionName, DistrictName FROM (

    SELECT
        CntApp = COUNT(app.ApplicationID)
        ,CntCon = 0
        ,r.RegionName
        ,d.DistrictName 
    FROM dim.Application app
        JOIN dim.Geography g ON (app.ApplicationID  = g.GeographyID)   
           AND (app.CountryId = g.CountryId)
        JOIN dim.Region r   ON r.RegionID = g.RegionID  
        JOIN dim.District d ON d.DistrictId = g.DistrictID
        JOIN dim.ZIPcode z  ON g.ZIPcodeID = z.ZIPcodeID         
    GROUP BY
        r.RegionName
        ,d.DistrictName

    UNION ALL

    SELECT
        CntApp = 0
        ,CntCon = COUNT(c.ContractID)
        ,r.RegionName
        ,d.DistrictName
    FROM dim.Contract c  
        JOIN dim.Geography g ON (c.ContractID = g.GeographyID)   
           AND (c.CountryId = g.CountryId)
        JOIN dim.Region r   ON r.RegionID = g.RegionID  
        JOIN dim.District d ON d.DistrictId = g.DistrictID
        JOIN dim.ZIPcode z  ON g.ZIPcodeID = z.ZIPcodeID         
    GROUP BY
        r.RegionName
        ,d.DistrictName
) d
GROUP BY RegionName, DistrictName

Answer 3

您需要FULL JOIN

SELECT coalesce(app.RegionName, c.RegionName) AS RegionName,
       coalesce(app.DistrictName, c.DistrictName) AS DistrictName,
      coalesce(app.CntApp,0) AS CntApp,
      coalesce(c.CntCon,0) AS CntCon
FROM 
    (SELECT
       CntApp = COUNT(app.ApplicationID)
       ,r.RegionName
       ,d.DistrictName 
    FROM dim.Application app
       JOIN dim.Geography g ON (app.ApplicationID  = g.GeographyID)   
         AND (app.CountryId = g.CountryId)
       JOIN dim.Region r   ON r.RegionID = g.RegionID  
       JOIN dim.District d ON d.DistrictId = g.DistrictID
       JOIN dim.ZIPcode z  ON g.ZIPcodeID = z.ZIPcodeID         
    GROUP BY
       r.RegionName
       ,d.DistrictName
    ) app
    FULL JOIN 
    (
       SELECT
       CntCon = COUNT(c.ContractID)
       ,r.RegionName
       ,d.DistrictName
    FROM dim.Contract c  
       JOIN dim.Geography g ON (c.ContractID = g.GeographyID)   
         AND (c.CountryId = g.CountryId)
       JOIN dim.Region r   ON r.RegionID = g.RegionID  
       JOIN dim.District d ON d.DistrictId = g.DistrictID
       JOIN dim.ZIPcode z  ON g.ZIPcodeID = z.ZIPcodeID         
    GROUP BY
       r.RegionName
       ,d.DistrictName
    ) c ON app.RegionName = c.RegionName AND app.DistrictName = c.DistrictName

Answer 4

您可能可以放弃联合，这将更加安全，因为如果坏数据进入g / r / d / z表，则结果将不受杂散笛卡尔联接的影响：

SELECT
 CntApp,
 CntCon,
 r.RegionName,
 d.DistrictName 
FROM 
 dim.Geography g  
 INNER JOIN dim.Region r   ON r.RegionID = g.RegionID  
 INNER JOIN dim.District d ON d.DistrictId = g.DistrictID
 INNER JOIN dim.ZIPcode z  ON g.ZIPcodeID = z.ZIPcodeID 

 LEFT JOIN (SELECT ApplicationID, CountryID, COUNT(*) CntApp FROM dim.Application GROUP BY ApplicationID, CountryID) app
   ON (app.ApplicationID  = g.GeographyID) AND (app.CountryId = g.CountryId)

 LEFT JOIN (SELECT ContractID, CountryId, COUNT(*) as CntCon FROM dim.Contract GROUP BY ContractID, CountryId) c    
   ON (c.ContractID = g.GeographyID) AND (c.CountryId = g.CountryId)

不过，这里有一些教育要点：

如果您有两个数据块（来自表，查询等），并且想要将它们垂直合并（更多行），则可以使用UNION。如果要水平将它们合并在一起（更多的列），则可以使用JOIN

如果我们有：

a,b,c
a,b,c
a,b,c

和

a,y,z
a,y,z
a,y,z

这是UNION的功能：

a,b,c
a,b,c
a,b,c
a,y,z
a,y,z
a,y,z

这就是您通过JOIN得到的结果：

a,b,c,y,z
a,b,c,y,z
a,b,c,y,z

记住这一点，会很好地为您服务