求高手指点！随机抽样问题！（急）
我有一张表mytable！比如里面只有3个字段,
mobile,province,city   都是char型
我现在要想随机查询表里的内容！

(mobile为手机号-前7个字符为手机的号段（比如13656565656   1365656为号段），共有80个号段，province为省份-已知有31个省)
条件：随机抽40个号段，10个省份，每个号段750个记录   共300000个记录！

请高手指点一下了！谢谢！


------解决方案--------------------
select * from (select *
row_number() over(order by mobile) as rownum,
rank() over(order by mobile) as rnk,
dense_rank() over(order by mobile) as densernk
from mytable where province in (
select top 10 distinct province,newid() as id from mytable order by id)
and mobile in
(select top 40 distinct mobile ,newid() as id from mytable order by id )
order by mobile ,province)
Where rnk <=750

你说MOBILE按前7位算，那看你的表结构中是如何存的了，如果分开存，你改一下字段就行了，否则你就用SUBSTRING函数就可以了。