MySQL-pivottabell med dynamiska rubriker baserade på en kolumndata

Ta en titt på den här liknande tråden där jag skrev en sp för att utföra uppgiften

Slå samman två tabeller (med ett 1-M-förhållande) där den andra tabellen måste "plattas till" till en rad

redigera. Uppdaterat svar

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)