复杂SQL加入帮助！

时间：2010-07-01 18:04:25

标签： sql left-join inner-join join

（如需快速回顾，请参阅标题为DATA的章节。只能在图A和图B中得到结果，我想要的是期望的结果，尝试在答案部分发布的所有内容。）

所有，我一直在努力开始在我的应用程序中巧妙地使用联接。男孩，我花了一段时间，但我想我已经掌握了这个，但我不能让这个查询工作。

请帮帮我！这是连接：

SELECT     TOP (100) PERCENT a.Id, a.DateCreated, a.DateModified, a.LastUpdatedBy, a.AccomplishmentTypeId, a.Title, a.Description, a.ApplicableDate, 
                  a.LocalId, at.Name AS AccomplishmentTypeName, a.Name AS AreaName, u.FirstName, u.LastName, ug.Name AS UserGroupName, 
                  ugo.Name AS OtherUserGroupName
FROM         dbo.Accomplishment AS a INNER JOIN
                  dbo.AccomplishmentType AS at ON at.Id = a.AccomplishmentTypeId INNER JOIN
                  dbo.AccomplishmentArea AS aal ON aal.AccomplishmentId = a.Id INNER JOIN
                  dbo.Area AS al ON al.Id = aal.AreaId INNER JOIN
                  dbo.UserAccomplishment AS ua ON ua.AccomplishmentId = a.Id INNER JOIN
                  dbo.[User] AS u ON u.Id = ua.UserId INNER JOIN
                  dbo.UserUserGroup AS uug ON uug.UserId = u.Id INNER JOIN
                  dbo.UserGroup AS ug ON ug.Id = uug.UserGroupId INNER JOIN
                  dbo.UserGroupType AS ugt ON ugt.Id = ug.UserGroupTypeId INNER JOIN
                  dbo.UserUserGroup AS uugo ON uugo.UserId = u.Id LEFT OUTER JOIN
                  dbo.UserGroup AS ugo ON ugo.Id = uugo.UserGroupId LEFT OUTER JOIN
                  dbo.UserGroupType AS ugto ON ugto.Id = ugo.UserGroupTypeId
WHERE     (ug.LocalId = 2) AND (ugo.LocalId <> 2) AND (ugto.LocalId = 4)
ORDER BY a.DateCreated DESC, u.LastName, u.FirstName, u.Id, UserGroupName

现在这有点复杂，但我正在做的是从所有这些相关表中选择信息，其中有成就，其中有一个用户与之关联，其中该用户具有用户组localId = 2，但是如果他们确实如此，我还想返回用户在usertype.localid = 4所在的所有用户组。

让我举一些示例数据，希望能够明确这一点，现在我在数据库中有3个成就，如下所示：

-------（DATA） 

Accomplishment 1:
   User: John
      Usergroups: Group A (Of UserGroupType 2), Group B (Of UserGroupType 3), 
                  Group C (Of UserGroupType 4), Group D (Of UsergroupType 4)
Accomplishment 2:
   User: John
      Usergroups: Group A (Of UserGroupType 2), Group B (Of UserGroupType 3), 
                  Group C (Of UserGroupType 4), Group D (Of UsergroupType 4)
Accomplishment 3:
   User: Sue
      Usergroups: Group A (Of UserGroupType 2)

现在我的上面的Join结果有4行：

-------（图A）： 

 Accomplishment 1, John, Group A, Group C
 Accomplishment 1, John, Group A, Group D
 Accomplishment 2, John, Group A, Group C
 Accomplishment 2, John, Group A, Group D

现在这是正确的，因为用户拥有的usergrouptype.localid为4的每个userGroup都有一行，但是，如何才能使它显示为完成3？我首先开始使用所有连接作为内部连接，然后考虑使用最后几个左连接将使用它来返回用户，即使它没有usergrouptype localid 4的用户组，但它没有。基本上我希望它返回组A中用户的任何成就，如果他们有任何usergrouptype 4的用户组，也返回所有这些用户组。

有什么想法？如果我不清楚请告诉我，这是非常复杂的，我可能没有足够的解释。

修改

（如需快速回顾，请参阅标题为DATA的章节。只能在图A和图B中得到结果，我想要的是期望的结果，尝试在答案部分发布的所有内容。）

HLGEM和Tom H.s结果都是相同的，更接近我的需要，但仍然关闭。现在我在图B中得到了9个结果。

-------（图B）： 

Accomplishment 1, John, Group A, Group C
Accomplishment 1, John, Group A, Group D
Accomplishment 1, John, Group A, Null
Accomplishment 1, John, Group A, Group B (Group B is UsergroupType 3)
Accomplishment 3, Sue, Group A, Null
Accomplishment 2, John, Group A, Group C
Accomplishment 2, John, Group A, Group D
Accomplishment 2, John, Group A, Null
Accomplishment 2, John, Group A, Group B (Group B is UsergroupType 3)

因此，出于某种原因，它包括John的空行，即使他的用户组是usergrouptype 4，并且它包含一个B组的行，该行是usergrouptype 3并且不应该出现。

再次编辑：

（如需快速回顾，请参阅标题为DATA的章节。只能在图A和图B中得到结果，我想要的是期望的结果，尝试在答案部分发布的所有内容。）

是的，我对此感到非常难过，我已经尝试了将一些东西放在where子句中的所有组合，它或者是没有成就3的4行，或者是9行，其中用户John每个成就获得两个额外的行，或者6行没有完成3和另一行用户组类型3用户组。更令人费解的是，将ugto.localid = 4添加到最后一行似乎对结果没有任何影响。它显示了我的用户组，其用户组类型为3，我在查询中没有看到任何可以的地方。

编辑5/02/10

（如需快速回顾，请参阅标题为DATA的章节。只能在图A和图B中得到结果，我想要的是期望的结果，尝试在答案部分发布的所有内容。）

我认为我想要的是不可能的如何设置？无论如何，我想要的结果是这5行：

-------（期望的结果）： 

Accomplishment 1, John, Group A, Group C
Accomplishment 1, John, Group A, Group D
Accomplishment 2, John, Group A, Group C
Accomplishment 2, John, Group A, Group D
Accomplishment 3, Sue, Group A, Null

以下列出了我尝试的所有内容及其结果:(请原谅蹩脚的SSMS格式）

以下所有内容均基于此基本查询：

启动查询/尝试1： 

SELECT     TOP (100) PERCENT a.Id, a.DateCreated, a.DateModified, a.LastUpdatedBy, a.AccomplishmentTypeId, a.Title, a.Description, a.ApplicableDate, 
                  a.LocalId, at.Name AS AccomplishmentTypeName, al.Name AS AreaName, u.FirstName, u.LastName, ug.Name AS UserGroupName, 
                  ugo.Name AS OtherUsergroupName
  FROM         dbo.Accomplishment AS a INNER JOIN
                  dbo.AccomplishmentType AS at ON at.Id = a.AccomplishmentTypeId INNER    JOIN
                  dbo.AccomplishmentArea AS aal ON aal.AccomplishmentId = a.Id INNER JOIN
                  dbo.Area AS al ON al.Id = aal.AreaId INNER JOIN
                  dbo.UserAccomplishment AS ua ON ua.AccomplishmentId = a.Id INNER JOIN
                  dbo.[User] AS u ON u.Id = ua.UserId INNER JOIN
                  dbo.UserUserGroup AS uug ON uug.UserId = u.Id INNER JOIN
                  dbo.UserGroup AS ug ON ug.Id = uug.UserGroupId INNER JOIN
                  dbo.UserGroupType AS ugt ON ugt.Id = ug.UserGroupTypeId INNER JOIN
                  dbo.UserUserGroup AS uugo ON uugo.UserId = u.Id LEFT OUTER JOIN
                  dbo.UserGroup AS ugo ON ugo.Id = uugo.UserGroupId AND ugo.LocalId <> 2 LEFT OUTER JOIN
                  dbo.UserGroupType AS ugto ON ugto.Id = ugo.UserGroupTypeId AND ugto.LocalId = 4
 WHERE     (ug.LocalId = 2)
 ORDER BY a.DateCreated DESC, u.LastName, u.FirstName, u.Id, UserGroupName

结果： 图B （见上文） 为什么会这么糟糕： John出现Nulls，并且出现了类型3的用户组。

尝试2：

尝试1，减去所有内联连接过滤，（仍保留最后两个的左连接）和以下where语句：

WHERE (ug.LocalId = 2)
  AND (ugo.LocalId <> 2 OR ugo.LocalId is null)
  AND (ugto.LocalId = 4 OR ugto.LocalId is null)

结果： 图A （见上文） 为何不好：不包括成就3

尝试3：

与尝试1相同，更改从此行开始：

 dbo.[User] AS u ON u.Id = ua.UserId INNER JOIN

该行下的变化：

                  dbo.UserUserGroup AS uug ON uug.UserId = u.Id INNER JOIN
                  dbo.UserGroup AS ug ON ug.Id = uug.UserGroupId AND ug.LocalId = 2 INNER JOIN
                  dbo.UserGroupType AS ugt ON ugt.Id = ug.UserGroupTypeId INNER JOIN
                  dbo.UserUserGroup AS uugo ON uugo.UserId = u.Id LEFT OUTER JOIN
                  dbo.UserGroup AS ugo ON ugo.Id = uugo.UserGroupId AND ugo.LocalId <> 2 LEFT OUTER JOIN
                  dbo.UserGroupType AS ugto ON ugto.Id = ugo.UserGroupTypeId
WHERE     (ugto.LocalId = 4)
ORDER BY a.DateCreated DESC, u.LastName, u.FirstName, u.Id, UserGroupName

（如需快速回顾，请参阅标题为DATA的章节。只能在图A和图B中得到结果，我想要的是期望的结果，尝试在答案部分发布的所有内容。）

5 个答案:

答案 0 :(得分：3)

@ ChaosPandion关于重新格式化的评论是一个好主意，但也许你需要一些帮助来理解什么是好格式。嗯，这对每个人来说可能都不一样:-)但如果我在编写你的查询，我会将其格式化如下：

SELECT  TOP (100) PERCENT
          a.Id,
          a.DateCreated,
          a.DateModified,
          a.LastUpdatedBy,
          a.AccomplishmentTypeId,
          a.Title,
          a.Description,
          a.ApplicableDate,  
          a.LocalId,
          at.Name AS AccomplishmentTypeName,
          a.Name AS AreaName,
          u.FirstName,
          u.LastName,
          ug.Name AS UserGroupName,  
          ugo.Name AS OtherUserGroupName 
FROM dbo.Accomplishment AS a
INNER JOIN dbo.AccomplishmentType AS at
  ON at.Id = a.AccomplishmentTypeId
INNER JOIN dbo.AccomplishmentArea AS aal
  ON aal.AccomplishmentId = a.Id
INNER JOIN dbo.Area AS al
  ON al.Id = aal.AreaId
INNER JOIN dbo.UserAccomplishment AS ua
  ON ua.AccomplishmentId = a.Id
INNER JOIN dbo.[User] AS u
  ON u.Id = ua.UserId
INNER JOIN dbo.UserUserGroup AS uug
  ON uug.UserId = u.Id
INNER JOIN dbo.UserGroup AS ug
  ON ug.Id = uug.UserGroupId
INNER JOIN dbo.UserGroupType AS ugt
  ON ugt.Id = ug.UserGroupTypeId
INNER JOIN dbo.UserUserGroup AS uugo
  ON uugo.UserId = u.Id
LEFT OUTER JOIN dbo.UserGroup AS ugo
  ON ugo.Id = uugo.UserGroupId
LEFT OUTER JOIN dbo.UserGroupType AS ugto
  ON ugto.Id = ugo.UserGroupTypeId 
WHERE ug.LocalId = 2 AND
      ugo.LocalId <> 2 AND
      ugto.LocalId = 4
ORDER BY a.DateCreated DESC,
         u.LastName,
         u.FirstName,
         u.Id,
         UserGroupName

我认为这种格式化更容易阅读。

分享并享受。

答案 1 :(得分：1)

我不确定我是否完全理解你要做的事情，但我认为你需要将你的标准移到LEFT OUTER JOIN中。如果将它放在WHERE子句中，那么如果LEFT OUTER JOIN找不到匹配项，那么这些列将显示为NULL，因此它们将无法通过WHERE子句检查。您实际上将LEFT OUTER JOIN转换为INNER JOIN。

FROM
    dbo.Accomplishment AS a
INNER JOIN dbo.AccomplishmentType AS at ON
    at.Id = a.AccomplishmentTypeId
INNER JOIN dbo.AccomplishmentArea AS aal ON
    aal.AccomplishmentId = a.Id
INNER JOIN dbo.Area AS al ON
    al.Id = aal.AreaId
INNER JOIN dbo.UserAccomplishment AS ua ON
    ua.AccomplishmentId = a.Id
INNER JOIN dbo.[User] AS u ON
    u.Id = ua.UserId
INNER JOIN dbo.UserUserGroup AS uug ON
    uug.UserId = u.Id
INNER JOIN dbo.UserGroup AS ug ON
    ug.Id = uug.UserGroupId AND
    ug.localid = 2
INNER JOIN dbo.UserGroupType AS ugt ON
    ugt.Id = ug.UserGroupTypeId
INNER JOIN dbo.UserUserGroup AS uugo ON
    uugo.UserId = u.Id
LEFT OUTER JOIN dbo.UserGroup AS ugo ON
    ugo.Id = uugo.UserGroupId AND
    ugo.localid <> 2
LEFT OUTER JOIN dbo.UserGroupType AS ugto ON
    ugto.Id = ugo.UserGroupTypeId
WHERE
    ugto.localid = 4
ORDER BY
    a.DateCreated DESC, u.LastName, u.FirstName, u.Id, UserGroupName

答案 2 :(得分：1)

在学习左连接时你犯了一个经典错误，你把条件放在where子句中将它们变成内连接

试试这个

SELECT     a.Id, a.DateCreated, a.DateModified, a.LastUpdatedBy, a.AccomplishmentTypeId, a.Title,
a.Description, a.ApplicableDate,  a.LocalId, at.Name AS AccomplishmentTypeName, 
a.Name AS AreaName, u.FirstName, u.LastName, ug.Name AS UserGroupName, ugo.Name AS OtherUserGroupName 
FROM        dbo.Accomplishment AS a 
INNER JOIN  dbo.AccomplishmentType AS at ON at.Id = a.AccomplishmentTypeId 
INNER JOIN  dbo.AccomplishmentArea AS aal ON aal.AccomplishmentId = a.Id 
INNER JOIN  dbo.Area AS al ON al.Id = aal.AreaId 
INNER JOIN  dbo.UserAccomplishment AS ua ON ua.AccomplishmentId = a.Id 
INNER JOIN  dbo.[User] AS u ON u.Id = ua.UserId 
INNER JOIN  dbo.UserUserGroup AS uug ON uug.UserId = u.Id 
INNER JOIN  dbo.UserGroup AS ug ON ug.Id = uug.UserGroupId 
INNER JOIN  dbo.UserGroupType AS ugt ON ugt.Id = ug.UserGroupTypeId 
INNER JOIN  dbo.UserUserGroup AS uugo ON uugo.UserId = u.Id 
LEFT OUTER JOIN  dbo.UserGroup AS ugo ON ugo.Id = uugo.UserGroupId  AND ugo.LocalId <> 2
LEFT OUTER JOIN  dbo.UserGroupType AS ugto ON ugto.Id = ugo.UserGroupTypeId  AND ugto.LocalId = 4
WHERE     ug.LocalId = 2 
ORDER BY a.DateCreated DESC, u.LastName, u.FirstName, u.Id, UserGroupName

请参阅此链接以获取对此的解释： http://wiki.lessthandot.com/index.php/WHERE_conditions_on_a_LEFT_JOIN

答案 3 :(得分：0)

这是我到目前为止重写的内容：

SELECT a.Id, a.DateCreated, a.DateModified, a.LastUpdatedBy, a.AccomplishmentTypeId, 
       a.Title, a.Description, a.ApplicableDate, a.LocalId, 
       at.Name AS AccomplishmentTypeName, a.Name AS AreaName, u.FirstName, 
       u.LastName, ug.Name AS UserGroupName, ugo.Name AS OtherUserGroupName
  FROM dbo.Accomplishment a 
  JOIN dbo.AccomplishmentType AS at ON at.Id = a.AccomplishmentTypeId 
  JOIN dbo.AccomplishmentArea AS aal ON aal.AccomplishmentId = a.Id 
  JOIN dbo.Area AS al ON al.Id = aal.AreaId 
  JOIN dbo.UserAccomplishment AS ua ON ua.AccomplishmentId = a.Id 
  JOIN dbo.[User] AS u ON u.Id = ua.UserId 
  JOIN dbo.UserUserGroup AS uug ON uug.UserId = u.Id 
  JOIN dbo.UserGroupType AS ugt ON ugt.Id = ug.UserGroupTypeId 
  JOIN dbo.UserGroup AS ug ON ug.Id = uug.UserGroupId 
  JOIN dbo.UserGroupType AS ugto ON ugto.Id = ug.UserGroupTypeId
 ORDER BY a.DateCreated DESC, u.LastName, u.FirstName, u.Id, UserGroupName

您有UserUserGroup的冗余加入，并且可以合并到UserGroup的加入，因为LEFT JOIN条件会取消之前加入到同一个表中的内容。

答案 4 :(得分：0)

你加入的都很好。这是过滤！

如果您编写的过滤器在左连接表中不允许空值，那么您的过滤器将删除左连接允许的其他记录。

LEFT JOIN

达到了ugo和ugto 
WHERE (ug.LocalId = 2)
  AND (ugo.LocalId <> 2 OR ugo.LocalId is null)
  AND (ugto.LocalId = 4 OR ugto.LocalId is null)

PS - 混合JOIN和FILTERING标准（在ON中或两者都在WHERE中）是一种精神错乱的方法。保持理智！

编辑：在联接中发现错误：

INNER JOIN dbo.UserUserGroup AS uugo ON uugo.UserId = u.Id

应该是

LEFT JOIN dbo.UserUserGroup AS uugo ON uugo.UserId = u.Id
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