MySql行转列、group_concat使用

CREATE TABLE `t_att` (
  `id` varchar(50) NOT NULL,
  `u_id` varchar(50) NOT NULL COMMENT '员id',
  `att_date` date DEFAULT NULL COMMENT '考勤日期',
  `att_type` tinyint(4) DEFAULT NULL COMMENT '考勤类型：1：出勤；2：出勤半天；3：请假；4：迟到；5：旷工',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='考勤信息'

select t.u_id as '员工id',t.att_date as '日期' from t_att t;

select t.u_id as '员工id',
       GROUP_CONCAT(t.att_date) '日期'
from t_att t 
group by t.u_id

show variables like '%lower%'