SQL在同一张表中连接两行数据

Question

我有以下表格:

Name   Type     Value
---------------------
mike   phone    123    
mike   address  nyc    
bob    address  nj    
bob    phone    333

我想要得到这样的结果：

name  value  value
-------------------
mike  nyc    123
bob   nj     333

我该怎么做呢？

- Dejell

Answer 1

这被称为自连接。诀窍是使用别名。

select 
    address.name,
    address.value as address,
    phone.value as phone
from
    yourtable as address left join
    yourtable as phone on address.name = phone.name
where address.type = 'address' and
      (phone.type is null or phone.type = 'phone')

该查询假定每个名称都有一个地址，但电话号码是可选的。

- cdonner

---

当你的回答出现时，我几乎逐字地在打这个。 - Chad

Answer 2

类似这样：

SELECT a.name AS name, phone, address
    FROM (SELECT name, value AS phone FROM mytable WHERE type = "phone") AS a
    JOIN (SELECT name, value AS address FROM mytable WHERE type = "address") AS b
    ON(a.name = b.name);

- Kerrek SB