工會一些兩場表到一個多場與第一場關鍵

這是醜陋的實現：工會一些兩場表到一個多場與第一場關鍵

select [keyfield] 
    , (MAX([f1])) as f1 
    , (MAX([f2])) as f2 
    , (MAX([f3])) as f3 
    , (MAX([f4])) as f4 
    , (MAX([f5])) as f5 

from (
    select [keyfield] 
     , [f1] 
     , Null as f2 
     , Null as f3 
     , Null as f4 
     , Null as f5 
    from t1 

    UNION ALL 

    select [keyfield] 
     , Null as f1 
     , [f2] 
     , Null as f3 
     , Null as f4 
     , Null as f5 
    from t2 

    UNION ALL 

    ... 
    ) subquery 
    group by subquery.[keyfield]

有沒有做同樣的其他方式？

來源

2013-12-23 Cynede

首先，你可以解決你的問題，你想做些什麼？你有六桌嗎？ – PeterRing

@PeterRing是的，我有5個2字段的表，並且想要得到一個6字段 – Cynede

好吧，那麼：你能描述表格，屬性等等，他們有什麼聯繫以及你想要什麼樣的解決方案？ – PeterRing

我覺得跟加入：

select [keyfield] 
    , (MAX([t1.f1])) as f1 
    , (MAX([t2.f2])) as f2 
    , (MAX([t3.f3])) as f3 
    , (MAX([t4.f4])) as f4 
    , (MAX([t5.f5])) as f5 

from t1 
Join t2 on t2.keyfield = t1.keyfield 
Join t3 on t3.keyfield = t1.keyfield 
Join t4 on t4.keyfield = t1.keyfield 
Join t5 on t5.keyfield = t1.keyfield 
Group by t1.keyfield

來源

2013-12-23 11:52:32 PeterRing

這隻適用於如果每個表都有當然，至少有一行（希望它有效，但）。理想情況下，多重性也是1：1，因此您不需要「GROUP BY」並進行聚合。 –

工會一些兩場表到一個多場與第一場關鍵

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