INNODB Engine中的Mysql AUTO_INCREMENT作为第二列

Question

i have a very annoying problem at this moment. i want a table with the following specification:

CREATE TABLE  `test` (
   `client` INT NOT NULL ,
   `id` INT NOT NULL AUTO_INCREMENT ,
   `test` INT NOT NULL ,
   PRIMARY KEY (  `client` ,  `id` ) ,
   INDEX (  `test` )
) ENGINE = INNODB;

you can see, that i have a primary key with 2 columns. now i want that the id auto_increment column only increments in order to the first column. for example:

## client/id ##
1/1 
1/2 
1/3
2/1
2/2
2/3

etc.

is this really impossible with innodb? i need innodb because of the transactional features.

Answer 1

You can derive it easily in SELECT statement

set @sno:=0;
set @client:='';
select @sno:=case when @client=client then @sno+1 else 1 end as sno,
@client:=client as client_id from table order by client;