Question

对于SQL来说，我是新手，上周工作时遇到了问题。我能够通过RoR查询完成它并根据我的需要重新格式化数据（凌乱的D :);但是，我真的想知道sql的解决方案，如果有任何

我有一个看起来像这样的MySQL数据库

| id | unique_visitors |      time_period    |
| 1  |              16 | 2013-07-01 00:00:00 |
| 2  |              20 | 2013-07-01 01:00:00 |
| 3  |               2 | 2013-07-01 02:00:00 |

我需要的最终输出看起来像这样

|    date    | 00 | 01 | 02 | 03 | 04 | 05 | 06 | 07 | 08 | 09 |.... | 22 | 23|
| 2013-07-01 | 16 | 20 |  2 | 32 | .........

每一行都会显示日期，每小时都会显示唯一身份访问者。

我不确定这是否可以使用sql查询，并且真的想借此机会学习一些东西。

谢谢SQL大师！

Answer 1

CASE语句变得复杂，但是你在这里。我觉得在睡觉之前是一个挑战

表统计信息（id，unique_visitors，time_period）

select DATE_FORMAT(time_period ,'%Y-%m-%d') as date, 
sum(CASE WHEN EXTRACT(hour from time_period)  =  00 THEN unique_visitors ELSE  0 END) as '00', 
sum(CASE WHEN EXTRACT(hour from time_period)  =  01 THEN unique_visitors ELSE  0 END) as '01', 
sum(CASE WHEN EXTRACT(hour from time_period)  =  02 THEN unique_visitors ELSE  0 END) as '02',  
sum(CASE WHEN EXTRACT(hour from time_period)  =  03 THEN unique_visitors ELSE  0 END) as '03',  
sum(CASE WHEN EXTRACT(hour from time_period)  =  04 THEN unique_visitors ELSE  0 END) as '04',  
sum(CASE WHEN EXTRACT(hour from time_period)  =  05 THEN unique_visitors ELSE  0 END) as '05',  
sum(CASE WHEN EXTRACT(hour from time_period)  =  06 THEN unique_visitors ELSE  0 END) as '06',  
sum(CASE WHEN EXTRACT(hour from time_period)  =  07 THEN unique_visitors ELSE  0 END) as '07',  
sum(CASE WHEN EXTRACT(hour from time_period)  =  08 THEN unique_visitors ELSE  0 END) as '08',  
sum(CASE WHEN EXTRACT(hour from time_period)  =  09 THEN unique_visitors ELSE  0 END) as '09',  
sum(CASE WHEN EXTRACT(hour from time_period)  =  10 THEN unique_visitors ELSE  0 END) as '10',  
sum(CASE WHEN EXTRACT(hour from time_period)  =  11 THEN unique_visitors ELSE  0 END) as '11',  
sum(CASE WHEN EXTRACT(hour from time_period)  =  12 THEN unique_visitors ELSE  0 END) as '12',  
sum(CASE WHEN EXTRACT(hour from time_period)  =  13 THEN unique_visitors ELSE  0 END) as '13',  
sum(CASE WHEN EXTRACT(hour from time_period)  =  14 THEN unique_visitors ELSE  0 END) as '14',  
sum(CASE WHEN EXTRACT(hour from time_period)  =  15 THEN unique_visitors ELSE  0 END) as '15',  
sum(CASE WHEN EXTRACT(hour from time_period)  =  16 THEN unique_visitors ELSE  0 END) as '16',  
sum(CASE WHEN EXTRACT(hour from time_period)  =  17 THEN unique_visitors ELSE  0 END) as '17',   
sum(CASE WHEN EXTRACT(hour from time_period)  =  18 THEN unique_visitors ELSE  0 END) as '18',  
sum(CASE WHEN EXTRACT(hour from time_period)  =  19 THEN unique_visitors ELSE  0 END) as '19',  
sum(CASE WHEN EXTRACT(hour from time_period)  =  20 THEN unique_visitors ELSE  0 END) as '20',  
sum(CASE WHEN EXTRACT(hour from time_period)  =  21 THEN unique_visitors ELSE  0 END) as '21',  
sum(CASE WHEN EXTRACT(hour from time_period)  =  22 THEN unique_visitors ELSE  0 END) as '22',  
sum(CASE WHEN EXTRACT(hour from time_period)  =  23 THEN unique_visitors ELSE  0 END) as '23' 
from stats
group by date
order by date

输出

      date  00  01  02  03  04  05  06  07  08  09  10  11  12  13 14  15  16  17  18  19  20  21  22  23
2013-07-01  22  16  2   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0
2013-07-02  0   0   0   0   30  0   0   0   50  0   0   0   0   0   0   0   15  0   0   0   0   0   0   0

-Jeff Weiss

SQL输出每小时的唯一访问者

1 个答案: