Oracle 查询结果未给出结果

Question

我有以下两张表

表A

     Name Location Group Value
     July   AAA    A    1
     Aug    BBB    B    2
     Sep    CCC    C    3
     Oct    DDD    D    4
     Nov    EEE    E    5

表 AA

 Name Location Group Value1
     July   AAA    A    6
     Aug    BBB    B    7
     Jan    CCC    C    8
     Oct    DDD    D    9
     Nov    FFF    F    10

我想要以下结果

Name Location Group Value Value1
 July   AAA    A       1    6
 Aug    BBB    B       2    7
 Jan    CCC    C            8
 Sep    CCC    C       3    
 Oct    DDD    D       4    9
 Nov    EEE    E       5    
 Nov    FFF    F            10

到目前为止，我已经使用了以下查询，但我无法得到结果..

SELECT A.Name, A.Location, A.Gruppo, A.value, AA.value1
FROM A
Full Outer Join AA
ON A.LOCATION=AA.LOCATION
and
A.GRUPPO=AA.GRUPPO
and 
A.name = AA.NAME

查询结果如下

 Name Location Gruppo value value 1
    July    AAA    A       1    6
    Aug     BBB    B       2    7
                                8
    Oct     DDD    D       4    9
                               10
    Sep     CCC    C       3    
    Nov     EEE    E       5    

谁能帮帮我。

Answer 1

你没有得到你想要的结果的原因是你没有告诉查询为连接条件中的列选择不为空的列。

例如，如果行同时出现在 A 和 AA 中（或仅出现在 A 中），则 a.name 不会为空。但是，如果该行仅出现在 AA 中，则 a.name 将为空。在这种情况下，您希望它显示 aa.name，您可以使用 COALESCE（或 NVL）来实现：

WITH a AS (SELECT 'July' NAME, 'AAA' LOCATION, 'A' "GROUP", 1 VALUE FROM dual UNION ALL
           SELECT 'Aug' NAME, 'BBB' LOCATION, 'B' "GROUP", 2 VALUE FROM dual UNION ALL
           SELECT 'Sep' NAME, 'CCC' LOCATION, 'C' "GROUP", 3 VALUE FROM dual UNION ALL
           SELECT 'Oct' NAME, 'DDD' LOCATION, 'D' "GROUP", 4 VALUE FROM dual UNION ALL
           SELECT 'Nov' NAME, 'EEE' LOCATION, 'E' "GROUP", 5 VALUE FROM dual),
    aa AS (SELECT 'July' NAME, 'AAA' LOCATION, 'A' "GROUP", 6 VALUE1 FROM dual UNION ALL
           SELECT 'Aug' NAME, 'BBB' LOCATION, 'B' "GROUP", 7 VALUE1 FROM dual UNION ALL
           SELECT 'Jan' NAME, 'CCC' LOCATION, 'C' "GROUP", 8 VALUE1 FROM dual UNION ALL
           SELECT 'Oct' NAME, 'DDD' LOCATION, 'D' "GROUP", 9 VALUE1 FROM dual UNION ALL
           SELECT 'Nov' NAME, 'FFF' LOCATION, 'F' "GROUP", 10 VALUE1 FROM dual)
-- end of mimicking your tables a and aa with data in them. See the SQL below:
SELECT coalesce(A.Name, aa.name) NAME,
       coalesce(A.Location, aa.location) LOCATION,
       COALESCE(A."GROUP", AA."GROUP") "GROUP",
       A.value,
       AA.value1
FROM   A
       Full Outer Join AA
         ON A.LOCATION = AA.LOCATION
            AND A."GROUP" = AA."GROUP"
            and A.name = AA.NAME;

NAME LOCATION GROUP      VALUE     VALUE1
---- -------- ----- ---------- ----------
July AAA      A              1          6
Aug  BBB      B              2          7
Jan  CCC      C                         8
Oct  DDD      D              4          9
Nov  FFF      F                        10
Sep  CCC      C              3 
Nov  EEE      E              5 

Answer 2

您可以选择 3 次，一次使用内部连接，两次使用左连接和排除。然后将它们合并为一个结果集：

SELECT A.Name, A.Location, A.Gruppo, A.Value, AA.Value1
FROM A
inner join AA
    ON  A.Location = AA.Location
    and A.Gruppo = AA.Gruppo
    and A.Name = AA.Name
union all
SELECT A.Name, A.Location, A.Gruppo, A.Value, AA.Value1
FROM A
left outer join AA
    ON  A.Location = AA.Location
    and A.Gruppo = AA.Gruppo
    and A.Name = AA.Name
where Value1 is null
union all
SELECT AA.Name, AA.Location, AA.Gruppo, A.Value, AA.Value1
FROM AA
left outer join A
    ON  A.Location = AA.Location
    and A.Gruppo = AA.Gruppo
    and A.Name = AA.Name
where Value is null