合并两个垂直表到一个水平表

本文介绍了合并两个垂直表到一个水平表的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

表定义

表1（水平）这是用户的一个表

Table 1 (horizontal) This is a table of users

| id | name | phone | --------------------- | 1 | Bob | 800 | | 2 | Phil | 800 |

表2（垂直表）这是球队的一个表

Table 2 (Vertical Table) This is a table of teams

| id | name | ------------------ | 1 | Donkey | | 2 | Cat |

表3（垂直表）此表是连接前两个

Table 3 (Vertical Table) This table is connecting the first two

| id | user_id | team_id | -------------------------- | 1 | 1 | 1 | | 2 | 1 | 2 | | 3 | 2 | 1 |

我的目标

我希望能够查询以这样的方式，我得到以下后面的数据：

I would like to be able to query the data in such a way that i get the following back:

| id | name | phone | Donkey | Cat | ------------------------------------- | 1 | Bob | 800 | 1 | 1 | | 2 | Phil | 800 | 1 | Null |

此表将有我的水平表数据，那么其它两个垂直的表的组合，以创建所附列。其中，表2最终被列名的标题。和行衣被合计从表三成一个布尔拉。

This table would have my horizontal table data, then a combination of the other two vertical tables to create the appended columns. Where table 2 ends up being the column name headings. And the row valus are pulled from table three as a boolean.

推荐答案

您在追逐一个数据透视表：

You're chasing a pivot table:

select u.*, sum(case when t1.name = 'Donkey' then 1 else 0 end) Donkey, sum(case when t1.name = 'Cat' then 1 else 0 end) Cat from users u inner join user_team ut1 on u.id = ut1.user_id inner join teams t1 on ut1.team_id = t1.id group by name

演示： sqlfiddle/#!9/5fd33/7