sql 函数
# 四则运算 + - * /
# 函数 distinct 、count、sum、max、min、avg、sum、round
select concat('device_id 是',device_id ) device_id from device_id_apply_factor where device_id ='D6A42CE6A0';
select concat_ws('|||',device_id ,factor_a ,module_type) from 、device_id_apply_factor where device_id ='D6A42CE6A0';
group_concat
select gender,name from student where js > 80 group by gender; 会报错
select gender, group_concat(name) from student where js > 80 group by gender;