Thread: auto-increment of primary key

i created a database like this, create table createpincode(id MEDIUMINT NOT NULL AUTO_INCREMENT,serialno char(30) Not NULL, pincode char(30)NOT NULL, type char(30)NOT NULL,primary key(1d));

public void createpins2(int pins, String type){
  String id=null;
try{
   pinlocal=pinhome.create(new Integer(id),serialno,pins,type){
catch(Exception ex){ex.getmessage();}

it works fine without the auto-increment, but now i'm havin an error at the JBOSS
The error is
EjbException in method: public abstract void sessions.NewSessionLocalBusiness.create(int,java.l ang.String):
javax.ejb.Exception:null
at Sessions.NewSessionBean.Createpins2(NewsseeionBean .java:271)
at sun.reflect.nativemethodAcessorImp.invoke(unknown source).

I think you have an issue when you try to pass in a null String into the Integer() constructor.

// Json