数据库查询次数

 CREATE TABLE `visits` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `user_id` int(11) DEFAULT NULL,
  `pages` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=gbk

insert into visits values(5,999,2);
insert into visits values(6,998,1);
insert into visits values(1,209,2);
insert into visits values(2,203,5);
insert into visits values(3,204,5);
insert into visits values(4,201,2);



//-------------------------
//累计访问 分别是 n1,n2 用户个数

select count(user_id),pages
from (
select id,user_id,pages
from visits
order by pages desc
)as s
group by s.pages;

//------------------------------
+----------------+-------+
| count(user_id) | pages |
+----------------+-------+
|              1 |     1 |
|              3 |     2 |
|              2 |     5 |
+----------------+-------+