[原创]关于分组序号在MySQL中的实现

1、表结构以及示例数据。

create table company
(dep char(10) not null,
val1 int unsigned not null
);
insert into company values 
('市场部', 26),
('市场部',25),
('市场部',24),
('办公室',16),
('办公室',12),
('研发部',19),
('研发部',11); 

2、存储过程

1）、循环实现

DELIMITER $$

CREATE DEFINER=`root`@`%` PROCEDURE `sp_generate_auto`()
BEGIN
 declare cnt int default 0;
 declare i int default 0; 
 drop table if exists tmp;
 -- Temporary table to save the result.
 create temporary table tmp like company;
 alter table tmp add num int unsigned not null;
 select count(1) as total from (select count(1) from company where 1 group by dep) T into cnt;
 while i < cnt
 do 
 set @stmt = concat('select dep from company where 1 group by dep order by dep asc limit ',i,',1 into @t_dep');
 prepare s1 from @stmt;
 execute s1;
 deallocate prepare s1;
 set @stmt = NULL;
 set @num = 0;
 set @stmt2 = concat('insert into tmp select dep,val1,@num := @num + 1 as sequence from company where dep = ''',@t_dep,''' order by dep asc');
 prepare s1 from @stmt2;
 execute s1;
 deallocate prepare s1;
 set @stmt2 = NULL;
 set i = i + 1;
 end while;
 select * from tmp;
 set @t_dep = NULL;
END$$

DELIMITER ;

2）、游标实现

DELIMITER $$

DROP PROCEDURE IF EXISTS `sp_generate_auto_cursor`$$

CREATE DEFINER=`root`@`%` PROCEDURE `sp_generate_auto_cursor`()

BEGIN

  declare done1 int default 0;

  declare a char(10);

  declare i int unsigned default 0;
 -- Cursor one to get the group total
  declare cur1 cursor for select dep from company group by dep;

  declare continue handler for 1329 set done1 = 1;

 -- Temporary table to save the result.
  drop table if exists tmp;

  create table tmp like company;

  alter table tmp add num int unsigned not null;

  open cur1;

  while done1 != 1

  do

    fetch cur1 into a;

    if not done1 then

      set @i = 0;

      begin

      declare done2 int default 0;

      declare b int unsigned default 0;

      declare c int unsigned default 0;
  -- Cursor two to get per group total.
      declare cur2 cursor for select val1,@i := @i + 1 from company where dep = a; 

      declare continue handler for 1329 set done2 = 1;

        open cur2;

        while done2 <> 1

        do

          fetch cur2 into b,c;

          if not done2 then

            insert into tmp select a,b,c;

          end if; 

        end while;

        close cur2;

      end;

    end if;

  end while;

  close cur1;

  select * from tmp;

END$$

DELIMITER ;


3、调用结果

call sp_generate_auto();
call sp_generate_auto_cursor();

query result(7 records)

uery result(7 records)

(7 row(s)returned)
(15 ms taken)

(0 row(s)affected)
(0 ms taken)

(7 row(s)returned)
(16 ms taken)

(0 row(s)affected)
(0 ms taken)