sql语句分组

比如数据如下

字段为 id ,v_name,v_value {{{ v_name v_value aa aa1 aa aa2 aa aa3 bb bb1 bb bb2 bb bb3 }}} 按v_name分组 如aa这一组,假设aa3为最新 bb这一组,假设bb1为最新 怎么样查询后使得记录为 {{{ aa aa3 bb bb1 }}} {{{ select t.v_name, (select v_value from test where v_name=t.v_name ORDER BY id DESC limit 1) as v_value FROM (select v_name from test group by v_name) AS t }}}