1：首先新建一个表并插入以下测试数据，如图

2：查询显示行号语句如下

　　　　select 
            @r := @r + 1 as rowNum,
            a.*
            from aopi as a , (select @r := 0 )as t
            order by a.id asc ;

3：显示结果如下图

 bye~