在不同条件下选择一条记录

给定这两个表：

打印配置文件：

 idprintprofile | empresa | remoteaddress 
----------------+---------+---------------
              6 | PDF     | 
              3 | HPR     | 
              2 | GAM     | 
              5 | TEST    | 
              7 | TEST    | 192.168.0.100

和

研究印刷品

 idstudyprint | empresa | remoteaddress 
--------------+---------+---------------
        12162 | TEST    | 
        12167 | GAM     | 
        12165 | GAM     | 
        12449 | TEST    | 192.168.0.100

I want to join these 和 get this:

 idstudyprint | empresa | idprintprofile | remoteaddress 
--------------+---------+----------------+---------------
        12449 | TEST    |              7 | 192.168.0.100
        12167 | GAM     |              2 | 
        12165 | GAM     |              2 | 
        12162 | TEST    |              5 | 

我提出的第一个问题是：

select                   
sp.idstudyprint, sp.empresa, pp.idprintprofile, sp.remoteaddress
from studyprint sp
join printprofiles pp on pp.empresa=sp.empresa
where
pp.remoteaddress = sp.remoteaddress or(pp.remoteaddress = '')
order by sp.created desc;

结果如下：

 idstudyprint | empresa | idprintprofile | remoteaddress 
--------------+---------+----------------+---------------
        12449 | TEST    |              5 | 192.168.0.100
        12449 | TEST    |              7 | 192.168.0.100
        12167 | GAM     |              2 | 
        12165 | GAM     |              2 | 
        12162 | TEST    |              5 | 

如您所见，idstudyprint = 12449重复，正确的应该是带有idprintprofile = 7的。