mysql 動態行轉列

表結果：
create table user(
id int ,
username varchar(10),
create_time datetime,
type int 
)

insert into user (`id`,`username`,`create_time`,`type`)
values ('1','張三','2019-04-25 14:36:41','1'),
('1','張三','2019-04-25 14:37:10','2'),
('1','張三','2019-04-25 14:37:26','1'),
('1','張三','2019-04-27 14:38:08','1'),
('1','張三','2019-04-26 14:36:02','1'),
('1','張三','2019-04-26 14:36:19','2'),
('1','李四','2019-04-25 14:39:50','1'),
('1','李四','2019-04-26 14:39:49','1'),
('1','李四','2019-04-26 14:39:48','1'),
('1','李四','2019-04-27 14:39:48','1'),
('1','李四','2019-04-27 14:39:44','1'),
('1','王五','2019-04-25 14:36:41','1');

數據表：

靜態用 case when then 

mysql  只能，動態用存儲 ，

SQL Server中行列轉換用 Pivot UnPivot

結果：

sql:

SET @str=''; 
set @sql_temp=''; 
SELECT @str:=CONCAT(@str,'sum(IF(left(create_time,10)=\'',create_time,'\'',',1,0)',') AS ' ,'''',create_time,'''',',') as aa into @sql_temp FROM (
SELECT left(create_time,10) as create_time  FROM `user` group by left(create_time,10)) A order by length(aa) desc limit 1; 
SET @result_sql=CONCAT('SELECT  user.username, ',LEFT(@sql_temp,char_length(@sql_temp)-1),'  FROM user GROUP BY username' ); 
PREPARE stmt FROM @result_sql; 
EXECUTE stmt ; 
deallocate prepare stmt