MySQL数据透视表,包含基于单列数据的动态标头
作者：互联网
我正在尝试编写一个查询来创建数据的“表”,如下所示：
SELECT cs.`category_id`, cs.`ProcessDate`, cs.`PercentChange`
FROM `Category_Statistics` cs
WHERE cs.`ProcessDate` >= '2011-05-10'
AND cs.`ProcessDate` <= '2011-05-14'
哪个会返回类似的东西：
CategoryId | ProcessDate | PercentChange
-------------------------------------------
category_4 | 2011-05-10 | 10
category_4 | 2011-05-11 | 18
category_4 | 2011-05012 | 12
...
category_7 | 2011-05-10 | 21
category_7 | 2011-05-11 | 7
...
category_12 | 2011-05-10 | 7
category_12 | 2011-05-11 | 15
现在我希望结果是这样的(来自MySQL查询,不受应用程序操纵)：
CategoryId | 2011-05-10 | 2011-05-11 | 2011-05-12 | 2011-05-13 | 2011-05-14 |
--------------------------------------------------------------------------------
category_4 | 10 | 18 | 12 | 9 | 14 |
category_7 | 21 | 7 | 16 | 14 | 13 |
categeory_12 | 7 | 15 | 11 | 19 | 8 |
--------------------------------------------------------------------------------
这有两点需要注意：
>日期范围可以增长或缩小
(取决于查询)
> PercentChange在某些情况下可能为null
案例(比如category_7 /
2011-05-12可能没有设定价值)
所以最终我不太确定如何构建查询的选择部分以反映动态数量的列(我知道它与CONCAT有关).
编辑 – >部分工作代码 – >
SELECT `CategoryId`,
MAX(IF(c.`ProcessedOn` = '2011-04-20', c.`PercentChange`, NULL)) AS '2011-04-20',
MAX(IF(c.`ProcessedOn` = '2011-04-21', c.`PercentChange`, NULL)) AS '2011-04-21',
MAX(IF(c.`ProcessedOn` = '2011-04-22', c.`PercentChange`, NULL)) AS '2011-04-22',
MAX(IF(c.`ProcessedOn` = '2011-04-23', c.`PercentChange`, NULL)) AS '2011-04-23',
MAX(IF(c.`ProcessedOn` = '2011-04-24', c.`PercentChange`, NULL)) AS '2011-04-24'
FROM `Category_Gravity` c
WHERE c.`ProcessedOn` >= '2011-04-20'
AND c.`ProcessedOn` <= '2011-04-24'
GROUP BY `CategoryId`
我现在要做的就是转
MAX(IF(c.`ProcessedOn` = '2011-04-20', c.`PercentChange`, NULL)) AS '2011-04-20',
变得更有活力(因为我的日期范围会改变)
解决方法:
看看这个类似的线程,我写了一个sp来完成任务
编辑.更新的答案
create table `pivot` (
`id` int(11) not null auto_increment,
`categoryid` int(11) default null,
`processdate` date default null,
`percentchange` int(11) default null,
primary key (`id`)
) engine=myisam auto_increment=9 default charset=latin1;
/*Data for the table `pivot` */
insert into `pivot`(`id`,`categoryid`,`processdate`,`percentchange`) values (1,4,'2011-05-10',1);
insert into `pivot`(`id`,`categoryid`,`processdate`,`percentchange`) values (2,4,'2011-05-11',22);
insert into `pivot`(`id`,`categoryid`,`processdate`,`percentchange`) values (3,4,'2011-05-12',3);
insert into `pivot`(`id`,`categoryid`,`processdate`,`percentchange`) values (4,7,'2011-05-10',4);
insert into `pivot`(`id`,`categoryid`,`processdate`,`percentchange`) values (5,7,'2011-05-11',5);
insert into `pivot`(`id`,`categoryid`,`processdate`,`percentchange`) values (6,12,'2011-05-10',6);
insert into `pivot`(`id`,`categoryid`,`processdate`,`percentchange`) values (7,12,'2011-05-12',7);
insert into `pivot`(`id`,`categoryid`,`processdate`,`percentchange`) values (8,4,'2011-05-13',12);
delimiter //
drop procedure if exists dynamic_view2//
create procedure dynamic_view2(in sdate date,in edate date)
begin
declare finish int default 0;
declare cdate date;
declare str varchar(10000) default "select categoryid,";
declare curs cursor for select processdate from pivot where processdate between sdate and edate group by processdate;
declare continue handler for not found set finish = 1;
open curs;
my_loop:loop
fetch curs into cdate;
if finish = 1 then
leave my_loop;
end if;
set str = concat(str, "max(case when processdate = '",cdate,"' then percentchange else null end) as `",cdate,"`,");
end loop;
close curs;
set str = substr(str,1,char_length(str)-1);
set @str = concat(str," from pivot
group by categoryid");
prepare stmt from @str;
execute stmt;
deallocate prepare stmt;
end;//
delimiter ;
mysql> call dynamic_view2('2011-05-10','2011-05-13');
+------------+------------+------------+------------+------------+
| categoryid | 2011-05-10 | 2011-05-11 | 2011-05-12 | 2011-05-13 |
+------------+------------+------------+------------+------------+
| 4 | 1 | 22 | 3 | 12 |
| 7 | 4 | 5 | NULL | NULL |
| 12 | 6 | NULL | 7 | NULL |
+------------+------------+------------+------------+------------+
3 rows in set (0.00 sec)
标签：mysql,pivot-table,dynamic 来源： https://codeday.me/bug/20190927/1824002.html