我的SQL UNION +极限

Question

这是我的查询

select PhoneNumber as _data,PhoneType as _type from contact_phonenumbers where ContactID = 3 and Type = 'R' and PT = 'M' 
union 
SELECT EmailID,Type from contact_emails where ContactID = 3 and Type = 'P' 
UNION 
SELECT EmailID,Type from contact_emails where ContactID = 3 and Type = 'O' 

这里我的问题是我需要从每个SELECT语句只获取一行。是否有可能通过“限制”来获取它。请帮助

Answer 1

根据MySQL的网站，你可以申请限制个人选择这样的

(SELECT a FROM t1 WHERE a=10 AND B=1 ORDER BY a LIMIT 10) 
UNION 
(SELECT a FROM t2 WHERE a=11 AND B=2 ORDER BY a LIMIT 10); 

http://dev.mysql.com/doc/refman/5.0/en/union.html