總結類似行

Question

想我也喜歡這樣的表：

NAME REF1 REF2 DRCT 
    A (null) Ra  D1 
    A  Rb (null) D1 
    A (null) Rc  D2 
    B  Rd (null) D3 
    B (null) Re  D3 

我想在像這樣聚集表：

NAME REF1 REF2 DRCT 
A  Rb  Ra  D1 
A (null) Rc  D2 
B  Rd  Re  D3 

正如你所看到的，我想用聚合相同的每一行名稱。我搜索了COALESCE和各種聚合函數，但是我還沒有找到我想要的東西。任何想法？

Answer 1

假設我問我在以前的評論是真實的，（只空或REF1和REF2每個名稱，DRCT對一個給定的值），這似乎工作：

select NAME, M_REF1, M_REF2, DRCT 
from (
    select A.NAME, coalesce(A.REF1, B.REF1) m_REF1, 
     coalesce(A.REF2, B.REF2) m_REF2, A.REF1 A_REF1, B.REF1 B_REF1, 
     A.REF2 A_REF2, B.REF2 B_REF2, A.DRCT 
    from Table1 A JOIN Table1 B on A.NAME = B.NAME AND A.DRCT = B.DRCT) 
    WHERE A_REF1 = m_REF1 AND B_REF2 = m_REF2 
UNION 
select A.NAME, A.REF1, A.REF2, A.DRCT 
FROM Table1 A JOIN 
    (select NAME, DRCT, COUNT(*) 
     from Table1 
     group by NAME, DRCT 
     HAVING COUNT(*) = 1) B ON A.NAME = B.NAME AND A.DRCT = B.DRCT; 

工會是因爲只有一個記錄的行不包含在第一個SELECT中。

但這是有點簡單，工程太：

select A.NAME, coalesce(A.REF1, B.REF1) M_REF1, coalesce(A.REF2,B.REF2) M_REF2,A.DRCT 
from Table1 A LEFT OUTER JOIN Table1 B ON A.DRCT = B.DRCT AND A.NAME = B.NAME 
WHERE NVL2(A.REF1,0,1) = 1 AND NVL2(B.REF1,0,1) =0 
     AND NVL2(A.REF2,0,1) = 0 AND NVL2(B.REF2,0,1) = 1 
UNION 
select A.NAME, A.REF1, A.REF2, A.DRCT 
FROM Table1 A JOIN 
(select NAME, DRCT, COUNT(*) 
    from Table1 
    group by NAME, DRCT 
    HAVING COUNT(*) = 1) B ON A.NAME = B.NAME AND A.DRCT = B.DRCT;