SQL - 使用左连接混合内连接

我有一个带有三个表的SQL Server数据库：Gang，GangMember和Neighborhood。这些表的结构是这样的：SQL - 使用左连接混合内连接

Neighborhood 
------------ 
ID (non-null) 
Name (non-null) 

Gang 
---- 
ID (non-null) 
Name (non-null) 
NeighborhoodID (nullable) 

GangMember 
---------- 
ID (non-null) 
GangID (non-null) 
Name (non-null), 
Position (nullable)

我需要得到团伙成员所属的（是的，他们可以属于多个）所有帮派。如果有邻居，我也需要返回。我想我的结果设置为以下形式：gang.name，neighborhood.name，member.position

到目前为止，我在这里得到：

SELECT 
g.[Name], 
'' as 'Neighborhood' /* This what I don't know how to do */ 
m.[Position] 
FROM 
    [Gang] g, 
    [GangMember] m 
WHERE 
    m.[GangID]=g.[ID]

因为帮派可能没有邻居，我不知道如何完成这个查询。有人可以帮我吗？谢谢！

来源

2011-09-05 user609886

我觉得你有你的模型的一些更新异常等问题。我不认为你已经正确定义了一个帮派成员，例如“帮派成员属于（是的，他们可以属于多个）”似乎是矛盾的。也许你的意思是说，同一个人*可以是同一个帮派的成员？如果是这样，大概他们可以在不同的帮派中以不同的名字（或相同的名字）知道他们自己的保护。了解帮派之间的竞争传统和他们的反建立性质，我很难想象哪个代理机构会是团伙成员ID的可信赖来源！ – onedaywhen

澄清：我认为你的'GangMember'表需要分成两个表格：一个用于模拟人（可能有诸如法定名称，指纹，DNA等标识符），另一个用于建模人和她的帮派（难以想象任何标识符，而不是'已知'的名字）。 – onedaywhen

试试这个：

SELECT 
    g.[Name], 
    n.[Name] as 'Neighborhood', 
    m.[Position] 
FROM 
    [Gang] g INNER JOIN [GangMember] m ON m.[GangID]=g.[ID] 
    LEFT OUTER JOIN [Neighborhood] n ON g.[NeighborhoodID] = n.[ID]

来源

2011-09-05 13:56:41 StevieG

select G.Name as GangName, 
     N.Name as Neighborhood, 
     GM.Name as MemberName, 
     GM.Position as MemberPosition 
from Gang as G 
    inner join GangMember as GM 
    on G.ID = GM.GangID 
    left outer join Neighborhood as N 
    on G.NeighborhoodID = N.ID

来源

2011-09-05 13:57:38

你可以做左连接如下：

SELECT 
g.[Name], 
n.name as 'Neighborhood' /* This what I don't know how to do */ 
m.[Position] 
FROM 
    [Gang] g 
    INNER JOIN [GangMember] m ON m.[GangID]=g.[ID] 
    LEFT JOIN Neighborhood n ON n.Id = g.NeighborhoodID

来源

2011-09-05 14:00:16 Leons

SELECT TOP (100) PERCENT 
    DemographicTable.Name, 
    ReferralTable.Code, 
    ReferralTable.Date_Termed, 
    ReferralTable.Referral_date, 
    (
     SELECT Date_Accepted 
     FROM CaseTable 
     WHERE (ReferralTable.ID = DemographicTable.ID_Number) 
      AND (Date_Accepted <> '') 
      AND (DateTermed > '2013-11-01' OR DateTermed = '') 
    ) AS Start, 
    (
     SELECT DateTermed 
     FROM CaseTable AS CaseTable_1 
     WHERE (ReferralTable.ID = DemographicTable.ID_Number) 
      AND (Date_Accepted <> '') 
      AND (DateTermed > '2013-11-01' OR DateTermed = '') 
    ) AS Term 
FROM ReferralTable 
INNER JOIN DemographicTable 
    ON ReferralTable.ID = DemographicTable.ID_Number 
    AND ReferralTable. Referral_date > '2012-12-01' 
    AND ReferralTable. Code = 'JTC' 
ORDER BY ReferralTable. Referral_date

来源

2014-04-25 17:25:57 crystaluser

SQL - 使用左连接混合内连接

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