1.需求
有如下访客访问次数的统计表 t_access
访客 月份 访问次数
A 2015-01 5
A 2015-01 15
B 2015-01 5
A 2015-01 8
B 2015-01 25
A 2015-01 5
A 2015-02 4
A 2015-02 6
B 2015-02 10
B 2015-02 5
…… …… ……
要求输出每个客户在每个月的总访问次数，以及在当前月份之前所有月份的累积访问次数。
输出表
访客 月份 月访问总计 累计访问总计
A 2015-01 33 33
A 2015-02 10 43
……. ……. ……. …….
B 2015-01 30 30
B 2015-02 15 45
……. ……. ……. …….
2.思路
1）第一步，先求每个用户的月总访问次数
select username,month,sum(count) as salary from t_access_times group by username,month
+-----------+----------+---------+--+
| username | month | count |
+-----------+----------+---------+--+
| A | 2015-01 | 33 |
| A | 2015-02 | 10 |
| B | 2015-01 | 30 |
| B | 2015-02 | 15 |
+-----------+----------+---------+--+
2）第二步，将月总访问次数表 自己连接 自己连接(内连接)
(select username,month,sum(count) as salary from t_access_times group by username,month) A
join
(select username,month,sum(count) as salary from t_access_times group by username,month) B
on
A.username=B.username
+-------------+----------+-----------+-------------+----------+-----------+--+
| a.username | a.month | a.salary | b.username | b.month | b.salary |
+-------------+----------+-----------+-------------+----------+-----------+--+
| A | 2015-01 | 33 | A | 2015-01 | 33 |
| A | 2015-01 | 33 | A | 2015-02 | 10 |
| A | 2015-02 | 10 | A | 2015-01 | 33 |
| A | 2015-02 | 10 | A | 2015-02 | 10 |
| B | 2015-01 | 30 | B | 2015-01 | 30 |
| B | 2015-01 | 30 | B | 2015-02 | 15 |
| B | 2015-02 | 15 | B | 2015-01 | 30 |
| B | 2015-02 | 15 | B | 2015-02 | 15 |
+-------------+----------+-----------+-------------+----------+-----------+--+
3）第三步，从上一步的结果中进行分组查询，分组的字段是a.username a.month，求月累计值： 将b.month <= a.month的所有b.salary求和即可
3.HQL
select A.username,A.month,max(A.count) ,sum(B.count)
from
(select username,month,sum(count) as count from t_accessgroup by username,month) A
inner join
(select username,month,sum(count) as count from t_access group by username,month) B
on
A.username=B.username
where B.month <= A.month
group by A.username,A.month
order by A.username,A.month;
