select 
    provinceName as '省份', 
    count(clientname) as '客户数', 
    sum(if(level='a', 1, 0)) as 'oa总额', 
    sum(if(level='b', 1, 0)) as 'ob总额', 
    sum(if(level='c', 1, 0)) as 'oc总额'
from 
    order 
    left join
    client
    on order.clientid = client.id
    left join
    province
    on client.privinceid = province.id
group by provinceName

------解决方案--------------------
http://blog.csdn.net/acmain_chm/article/details/4283943
MySQL交叉表
在某些数据库中有交叉表，但在MySQL中却没有这个功能，但网上看到有不少朋友想找出一个解决方法，特发贴集思广义。http://topic.csdn.net/u/20090530/23/0b782674-4b0b-4cf5-bc1a-e8914aaee5ab.html?96198现整理解法如下：数据样本： create table tx(  id int primary key,  c1 c...