Question

我有两张桌子：

declare @Table1 as table (id int, value CHAR(1))
declare @Table2 as table (id int, value CHAR(1))

INSERT @Table1
VALUES (1, 'A'),
(1, 'B'),
(3, 'A')

INSERT @Table2
VALUES(1, 'A'),
(1, 'C'),
(2, 'A')

我想加入这两个表，以便最后我能够产生这个结果：

id     value    id      value
1      A        1       A
1      B        NULL    NULL
NULL   NULL     1       C

我很抱歉没有充分的解释（我的意思是根本没有解释）。我在这里尝试做的是（类似的）为id列创建内部联接（我的意思是在“id”列上获取两个集合中常见的记录）然后查看值列并在里面比较它们这个共同集的边界。

我希望我可以描述一下我的目的。

Answer 1

希望这会起作用

SELECT distinct t1_id as id, t1_value as value , t2_id as id , t2_value as value
FROM (SELECT t1.id as t1_id, t1.value as t1_value from @Table1  t1 INNER JOIN @Table2 t2 on t1.id = t2.id) as A 
        FULL OUTER JOIN 
     (SELECT  t2.id as t2_id, t2.value as t2_value  from @Table1  t1 INNER JOIN  @Table2 t2 on t1.id = t2.id) as B
    on A.t1_value = B.t2_value
ORDER BY t1_id desc

基本上，我正在做的是在内部集合的值列上外部连接内部集合（在id列上的内部联接）。

Answer 2

我赢了什么？

SELECT c.id,c.value,d.id,d.value

FROM
    @Table1 c
    full join
    @Table2 d 
        on c.id = d.id and c.value = d.value
WHERE exists
        (
        SELECT a.id
            FROM
                @Table1 a
            INNER JOIN
                @Table2 b
                  ON a.id = b.id and a.id = c.id or d.id = a.id

        )

Answer 3

您可以通过预过滤表格，使用full outer join 和执行此操作：

select a.id as a_id, a.value as a_value,
       b.id as b_id, b.value as b_value
from (select *
      from tablea a
      where a.id = 1
     ) a full outer join
     (select *
      from tableb b
      where b.id = 1
     ) b
     on a.id = b.id and a.value = b.value;

内连接然后在匹配的记录中完全连接

3 个答案: