CREATE TABLE my_tb (
id int(11) NOT NULL AUTO_INCREMENT,
parent_code varchar(255) DEFAULT NULL,
code varchar(255) DEFAULT NULL,
PRIMARY KEY (id)
) ENGINE=InnoDB AUTO_INCREMENT=8 DEFAULT CHARSET=utf8;

INSERT INTO `my_tb` (  `parent_code`, `code`) VALUES ('01', '001');
INSERT INTO `my_tb` (  `parent_code`, `code`) VALUES ('01', '002');
INSERT INTO `my_tb` (  `parent_code`, `code`) VALUES ('02', '001');
INSERT INTO `my_tb` (  `parent_code`, `code`) VALUES ('01', '003');
INSERT INTO `my_tb` (  `parent_code`, `code`) VALUES ('02', '002');
INSERT INTO `my_tb` (  `parent_code`, `code`) VALUES ('03', '001');
INSERT INTO `my_tb` (  `parent_code`, `code`) VALUES ('04', '001');

-- 生成 行号
select @r:=@r+1 as row_num , a.* from  my_tb a ,(select @r:=0) b



-- 生成 分组排序号

select  
     @group_row:=CASE when @parent_code=a.parent_code then  @group_row+1 else 1 end as groupRow,
     @parent_code:=a.parent_code as parent_code,
     a.code  

  from  my_tb a ,( select @group_row:=1, @parent_code:='') as b
 ORDER BY   a.parent_code , a.code

查询结果

"groupRow"	"parent_code"	"code"
"1"	"01"	"001"
"2"	"01"	"002"
"3"	"01"	"003"
"1"	"02"	"001"
"2"	"02"	"002"
"1"	"03"	"001"
"1"	"04"	"001"

https://blog.csdn.net/kxjrzyk/article/details/58588000