class dal
{
  private dcDataContext dc;
        public dal()
        { dc = new dcDataContext(); }


        public bbei tbid(long tbid)//输入id返回bbei对象
        {
            return dc.bbei.Where(q => q.tbid == tbid).First();
        }
}

class BLL 
    {
 private bbei bb;
        private dcDataContext dc;
public BLL()
        { bb = new bbei(); dc = new dcDataContext(); }


 public bool upda(long id)
        {
   bb = dal.tbid(id); //根据id返回对象
bb.name="张三";  //修改name为张三
dc.SubmitChanges(); //同步到数据库