Question

CREATE TABLE  practice_mysql.sample (  id int(11) default NULL,  Firstname varchar(45) default NULL ) ENGINE=InnoDB DEFAULT CHARSET=utf8;

insert into sample (id,Firstname) values ('1','Anish');
insert into sample (id,Firstname) values ('2','Anish');
insert into sample (id,Firstname) values ('3','Uma');
insert into sample (id,Firstname) values ('4','Anish');
insert into sample (id,Firstname) values ('5','Uma');
insert into sample (id,Firstname) values ('6','temp');

**

和我尝试这个查询获取名字前3个字母和我有用于生成自动增量

**

SET @ndx = 0;
SET @cur_hash = '';
SELECT id,Firstname ,CONCAT(left(Firstname ,3),IF(ndx>=0,CONCAT('--00',ndx),'')) BatchNumber
FROM (SELECT id,
   @new_hash := MD5(Firstname ),
   (@ndx := IF(@new_hash=@cur_hash,@ndx+1,1)) ndx,
   @cur_hash := MD5(Firstname ),
   Firstname
FROM (SELECT id,Firstname FROM sample ORDER BY Firstname ) AA) A order by id;

我尝试了这段代码，但输出错误。这里有什么错误？

    Firstname | Batchnumber
    ---------------------

    Anish     |  Ani001
    Anish     |  Ani001
    Uma       |  Uma001
    Anish     |  Ani001
    Uma       |  Uma001
    temp      |  tem001

但我需要这种类型的输出：

    Firstname | Batchnumber
    -----------------------

       Anish     |  Ani001
       Anish     |  Ani002
       Uma       |  Uma001
       Anish     |  Ani003
       Uma       |  Uma002
       temp      |  tem001

当多次插入名称时，我增加了批号。但它不起作用。我会尝试自己找到它，但对我来说很难。任何人都可以解决它吗？

批号不会增加

0 个答案: