复杂的SQL Join帮助！

Question

（有关快速回顾，请参见标题为DATA的部分。只能在图A和图B中获得结果，我想要的是所需的结果，请尝试在答案部分中发布的所有内容。）

总而言之，我一直在努力从我的应用程序中聪明地开始使用联接。 男孩花了我一段时间，但我想我已经掌握了这个主意，但是我无法使该查询正常工作。

请帮我！ 这是按原样的联接：

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，但是我正在做的是从所有相关表中选择一项有成就的信息，其中有一个与之相关联的用户，而该用户的用户组的localId = 2，但是如果确实有，我还想返回该用户所在的所有用户组，其中usertype.localid = 4。

让我给出一些示例数据来希望使这一点变得清楚，现在我在数据库中有3个如下所示的成就：

- - - -（数据）

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)

现在我上面的Join结果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，因为该用户拥有的每个userGroup都有一行，其usergrouptype.localid为4，但是，如何使其显示完成3？ 我首先将所有联接作为内部联接开始，然后认为进行最后的几个左联接将使它返回用户，即使它没有用户组类型为localid 4的用户组，也没有。 基本上，我希望它返回组A中用户的任何成就，并且如果他们具有usergrouptype 4的任何用户组，则也返回所有这些用户组。

有什么想法吗？ 如果我不清楚，请告诉我，这太复杂了，我可能还没有足够的解释。

编辑：

（有关快速回顾，请参见标题为DATA的部分。只能在图A和图B中获得结果，我想要的是所需的结果，请尝试在答案部分中发布的所有内容。）

HLGEM和Tom Hs的结果都相同，虽然更接近我的需求，但仍然相差甚远。 现在，在图B中我得到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，即使John的用户组的用户组类型为4，该行也包含空行，并且其中包含组B的行的用户组类型为3，因此不应显示该行。

再次编辑：

（有关快速回顾，请参见标题为DATA的部分。只能在图A和图B中获得结果，我想要的是所需的结果，请尝试在答案部分中发布的所有内容。）

是的，我确实为此感到困惑，我已经尝试了将东西放在where子句中的几乎每一种组合，它要么是4行没有成就3，要么是9行，其中用户John每个成就又获得了2行，或者6行没有完成3和usergrouptype 3用户组的额外行。 更令人困惑的是，在最后一行添加ugto.localid = 4似乎对结果没有任何影响。 它向我显示了一个用户组，该用户组的用户组类型为3，在查询的任何地方都看不到。

编辑5/02/10

（有关快速回顾，请参见标题为DATA的部分。只能在图A和图B中获得结果，我想要的是所需的结果，请尝试在答案部分中发布的所有内容。）

我认为我希望它的设置是不可能的吗？ 无论如何，我想要的结果是这5行：

-------（所需结果）：

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

这是我尝试过的所有内容及其提供的结果的列表：（请原谅糟糕的SSMS格式）

以下所有内容均基于此基本查询：

开始查询/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 （请参见上面的方法） 为什么不好：出现 John的Null并显示类型3的用户组。

尝试2：

尝试1，减去所有的内联联接筛选（仍然在最后两个联接上保持左联接）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 （请参见上面的方法） 不好的原因：不包括成就3

尝试3：

与尝试1相同，但在此行下开始更改：

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

在该行下的更改：

                  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

（有关快速回顾，请参见标题为DATA的部分。只能在图A和图B中获得结果，我想要的是所需的结果，请尝试在答案部分中发布的所有内容。）

Answer 1

@ChaosPandion关于重新格式化的评论是一个好主意，但是也许您需要一些帮助来了解什么是好的格式。 好吧，对于每个人来说，它可能都不同:-)，但是如果我正在编写查询，我将其格式设置如下：

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

我认为这种格式使其更易于阅读。

分享并享受。

Answer 2

我不确定我是否完全了解您要执行的操作，但是我认为您需要将标准移至“左外部联接”中。 如果将其放在WHERE子句中，则如果LEFT OUTER JOIN未找到匹配项，则这些列将显示为NULL，因此它们将无法通过WHERE子句检查。 您实际上是在将“左外部连接”转换为“内部连接”。

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

Answer 3

在学习左联接时，您犯了一个经典错误，您在where子句中放置了将其变为内部联接的条件

尝试这个

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

Answer 4

到目前为止，这是我重写的内容：

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

您有一个到UserUserGroup的多余UserUserGroup ，并且可以合并到UserGroup的联接，因为LEFT JOIN条件将取消上一次联接到同一表的操作。

Answer 5

您的联接都很好。 这是过滤！

如果编写的过滤器不允许左连接表中的空值，那么您的过滤器将删除左连接允许的其他记录。

ugo和ugto均可通过LEFT JOIN到达

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或在WHERE中都使用）是导致精神错乱的秘诀。 保持理智！

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编辑：在连接中发现错误：

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

应该

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