Question

T1 table

+-----------+------------------+
| cookie_id |    impression    |
+-----------+------------------+
|       123 |          6/17/15 |
|       123 |          6/18/15 |
|       123 |          6/18/15 |
|       234 |          6/20/15 |
|       234 |          6/22/15 |
+-----------+------------------+

T2 table
+-----------+---------+---------+---------+
| cookie_id |   HP    | search  |  book   |
+-----------+---------+---------+---------+
|       123 | 6/17/15 |         |         |
|       123 | 6/18/15 |         |         |
|       123 |         | 6/18/15 |         |
|       123 |         |         | 6/19/15 |
|       234 | 6/23/15 |         |         |
|       234 |         | 6/25/15 |         |
|       234 |         |         | 6/29/15 |
+-----------+---------+---------+---------+

我们希望将T1和T2加入预期结果，如下表T3所示：

+-----------+------------+---------+---------+---------+
| cookie_id | impression |   HP    | search  |  book   |
+-----------+------------+---------+---------+---------+
|       123 | 6/17/15    |         |         |         |
|       123 | 6/18/15    |         |         |         |
|       123 | 6/18/15    |         |         |         |
|       123 |            | 6/17/15 |         |         |
|       123 |            | 6/18/15 |         |         |
|       123 |            |         | 6/18/15 |         |
|       123 |            |         |         | 6/19/15 |
|       234 | 6/20/15    |         |         |         |
|       234 | 6/22/15    |         |         |         |
|       234 |            | 6/23/15 |         |         |
|       234 |            |         | 6/25/15 |         |
|       234 |            |         |         | 6/29/15 |
+-----------+------------+---------+---------+---------+

Answer 1

http://sqlfiddle.com/#!9/375e6/2

SELECT cookie_id, impression, null,null, null
FROM t1
UNION ALL
SELECT cookie_id, null as impression, hp, search,book
FROM t2

Answer 2

正如评论中所提到的，你似乎想要UNION这些表：这样做会，但它可能不是你真正需要的......

SELECT * FROM (
    (SELECT cookie_id, 
            "" AS impression, 
            HP, 
            search, 
            book 
     FROM T1)
     UNION
    (SELECT cookie_id, 
            impression, 
            "" AS HP, 
            "" AS search, 
            "" AS book
     FROM T2)
    ) a
ORDER BY cookie_id;

这不是我的想法，也许我写错了什么的。

如何在SQL中连接表

2 个答案: