将两个垂直表合并到一个水平表-数据库问题

Merging two vertical tables onto one horizontal table(将两个垂直表合并到一个水平表)

本文介绍了将两个垂直表合并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

表格定义

Table 1 (horizontal) 这是一个用户表

Table 1 (horizontal) This is a table of users

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

Table 2 (Vertical Table) 这是一个团队表

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

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

Table 3 (Vertical Table) 此表连接前两个

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     |

<小时>

我的目标

我希望能够以返回以下信息的方式查询数据:

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 |

此表将包含我的水平表数据，然后是其他两个垂直表的组合以创建附加列.表 2 最终成为列名标题.并且行值作为布尔值从表三中提取.

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

您正在寻找数据透视表:

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:http://sqlfiddle.com/#!9/5fd33/7

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