SQL在同一個表

Question

加入2行，我有以下表格：

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

我想有結果是這樣的：

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

我該怎麼辦呢？

Answer 1

它被稱爲自連接。訣竅是使用別名。

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') 

該查詢假定每個名稱都有一個地址，但電話號碼是可選的。

Answer 2

事情是這樣的：

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);