早上有人求助，我写出答案如下，觉得这个问题还算有代表性：
不过MYSQL的预处理好像得用动态变量，静态的不认。老出错。
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表[A],2个字段，name,num,
数据为：
name num
tom 3
jerry 2
jessic 2
lily 1


希望通过一段SQL语句得到以下的数据集：
tom
tom
tom
jerry
jerry
jessic
jessic
lily

就是根据NUM的值，重复几次NAME。

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贴出完成版
create table test(name varchar(64),num int(11));
insert into test values('tom',3),('jerry',2),('jessic',2),('lily',1);
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DELIMITER $$

DROP PROCEDURE IF EXISTS `test`.`sp_test`$$

CREATE PROCEDURE `test`.`sp_test`()

BEGIN

declare cnt int(11);

declare i int(11);

declare j int(11);

  create temporary table num (name varchar(64),num int(11));

  select count(*) from test where 1 = 1 into cnt;

  set i = 0;

  loop1:loop

    set @query1 = concat('select name,num from test limit ',i,',1 into @name,@num1');

    prepare stmt1 from @query1;

    execute stmt1;

    deallocate prepare stmt1;

    set j = 1;

    loop2:loop

      set @query2 = 'insert into num values(?,?)';

      prepare stmt2 from @query2;

      execute stmt2 using @name,@num1;

      deallocate prepare stmt2;    

      set j = j + 1;

      if j > @num1 then

        leave loop2;

      end if;

    end loop loop2;

    set i = i + 1;

    if i > cnt -1 then

      leave loop1; 

    end if;

  end loop loop1;

  select name  from num;   

    

END$$

DELIMITER ;

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call sp_test();

query result(8 records)

name    

tom     

tom     

tom     

jerry   

jerry    

jessic    

jessic    

lily     

本文转自 david_yeung 51CTO博客，原文链接：http://blog.51cto.com/yueliangdao0608/81398，如需转载请自行联系原作者