Question

下面是我尝试加入的2个表，

表1：

+--------+--------+---------+------+-----+--------+
| seq_id | req_id | ctrl_id | CODE | c2  | status |
+--------+--------+---------+------+-----+--------+
|      1 |      3 | C001    | ABC  |   0 | PASS   |
|      2 |      3 | C001    | EFG  |   0 | PASS   |
|      3 |      3 | C001    | HIJ  |   0 | PASS   |
+--------+--------+---------+------+-----+--------+

表2：

+--------+--------+---------+--------+-------+-------------+
| seq_id | Req_id | ctrl_id | source |  c1   |     c2      |
+--------+--------+---------+--------+-------+-------------+
|      1 |      5 | C001    | S1     |   ABC | 32331235662 |
|      2 |      5 | C001    | S1     |   EFG |  8966492700 |
|      3 |      5 | C001    | S1     |   HIJ | 12656678121 |
|      4 |      5 | C001    | S2     |   ABC | 32331235662 |
|      5 |      5 | C001    | S2     |   EFG |  8966492700 |
|      6 |      5 | C001    | S2     |   HIJ | 12656678121 |
+--------+--------+---------+--------+-------+-------------+

我正在使用以下查询联接这些表，

select a.seq_id, a.req_id, a.ctrl_id, a.CODE,
       (case when b.source = 'S1' then  b.c2 end) as source1 ,   
       (case when b.source = 'S2' then  b.c2 end) as source2, a.c2, a.status
from table1 a  
  join  table2 b on  a.ctrl_id=b.ctrl_id  and a.code=b.c1
order by a.seq_id

我得到的结果是

seq_id  Req_id  ctrl_id CODE    SOURCE1          SOURCE2        c2  status
1          5    C001    ABC      NULL             32331235662   0   PASS
1          5    C001    ABC      32331235662      NULL          0   PASS
2          5    C001    EFG      NULL             8966492700    0   PASS
2          5    C001    EFG      8966492700       NULL          0   PASS
3          5    C001    HIJ      NULL             12656678121   0   PASS
3          5    C001    HIJ      12656678121      NULL          0   PASS

我正在尝试获取以下结果，而没有空值

seq_id  Req_id  ctrl_id CODE    SOURCE1          SOURCE2        c2  status
1          5    C001    ABC      32331235662      32331235662   0   PASS
2          5    C001    EFG      8966492700       8966492700    0   PASS
3          5    C001    HIJ      12656678121      12656678121   0   PASS

请协助。

Answer 1

只需将分组用于此任务

select a.seq_id, a.req_id, a.ctrl_id, a.CODE,
       max(case when b.source = 'S1' then  b.c2 end) as source1 ,   
       max(case when b.source = 'S2' then  b.c2 end) as source2, a.c2, a.status
from table1 a  
  join  table2 b on  a.ctrl_id=b.ctrl_id  and a.code=b.c1
group by a.seq_id, a.req_id, a.ctrl_id, a.CODE,a.c2, a.status
order by a.seq_id

Answer 2

您可以使用联接来获取要使用的两个单独的字段，然后将它们修改为原始数据集。

在这种情况下，联接是到同一表的SELF JOINS，以获得指定的值。

    select a.seq_id, b.req_id, a.ctrl_id, a.CODE,
           s1.c2 AS [Source1] ,
           s2.c2 AS [Source2],
           a.c2,
           a.status
    from table1 a  
      LEFT OUTER JOIN table2 b 
            ON a.seq_id = b.seq_id
      LEFT OUTER JOIN table2 s1
            ON s1.req_id = b.req_id AND s1.c1 = b.c1 AND s1.[source] = 'S1'
      LEFT OUTER JOIN table2 s2
            ON s2.req_id = b.req_id AND s2.c1 = b.c1 AND s2.[source] = 'S2'
    order by a.seq_id

联接两个表，结果中没有空值

2 个答案: