mysql 表联合和新列

Question

给两个后续 tables,

phone table:

 PID   NAME
1001 iphone
1002 samsung
1003 sony

pc table:

 CID  NAME
1001 HP
1002 XPS

我怎样才能得到结果table？

  DID  TYPE NAME
 1001 PHONE iphone
 1002 PHONE samsung
 1003 PHONE sony
 1001 PC    HP
 1002 PC    XPS

我觉得这个应该用UNION，但是这个TYPE怎么处理呢？

Answer 1

如果你也想复制结果，你应该使用 UNION ALL，否则你可以使用 UNION 来消除重复值。

您的查询将是这样的，

select pid as DID,'PHONE' as TYPE,name from phone
UNION all
select CID as DID,'PC' as TYPE,name from PC;

这将 select 两个表中的所有记录。

Answer 2

SELECT PID AS DID, 'PHONE' AS TYPE, NAME FROM Phone
UNION ALL
SELECT CID AS DID, 'PC' AS TYPE, NAME FROM PC;

Answer 3

使用这个查询：

select pid as DID,'PHONE' as TYPE, name from phone
UNION 
select cid as DID,'PC' as TYPE, name from PC;

mysql tables union and new column