mysql查询出来的某一列合并成一个字段详解数据库

select u.*,sr.* 
    from users u 
    left join sys_user_role sur on sur.userCode=u.id 
    left join sys_role sr on sr.roleCode=sur.roleCode

select u.*,GROUP_CONCAT(DISTINCT(sr.roleCode))  
    from users u 
    left join sys_user_role sur on sur.userCode=u.id 
    left join sys_role sr on sr.roleCode=sur.roleCode 
    group by u.userCode