SQL - 使用左連接混合內連接

我有一個帶有三個表的SQL Server數據庫：Gang，GangMember和Neighborhood。這些表的結構是這樣的：SQL - 使用左連接混合內連接

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)

我需要得到團伙成員所屬的（是的，他們可以屬於多個）所有幫派。如果有鄰居，我也需要返回。我想我的結果設置爲以下形式：gang.name，neighborhood.name，member.position

到目前爲止，我在這裏得到：

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]

因爲幫派可能沒有鄰居，我不知道如何完成這個查詢。有人可以幫我嗎？謝謝！

來源

2011-09-05 user609886

我覺得你有你的模型的一些更新異常等問題。我不認爲你已經正確定義了一個幫派成員，例如「幫派成員屬於（是的，他們可以屬於多個）」似乎是矛盾的。也許你的意思是說，同一個人*可以是同一個幫派的成員？如果是這樣，大概他們可以在不同的幫派中以不同的名字（或相同的名字）知道他們自己的保護。瞭解幫派之間的競爭傳統和他們的反建立性質，我很難想象哪個代理機構會是團伙成員ID的可信賴來源！ – onedaywhen

澄清：我認爲你的'GangMember'表需要分成兩個表格：一個用於模擬人（可能有諸如法定名稱，指紋，DNA等標識符），另一個用於建模人和她的幫派（難以想象任何標識符，而不是'已知'的名字）。 – onedaywhen

試試這個：

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]

來源

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

來源

2011-09-05 13:57:38

你可以做左連接如下：

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

來源

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

來源

2014-04-25 17:25:57 crystaluser

SQL - 使用左連接混合內連接

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