db.createConnection db是什么对象啊?

SqlConnection mycon=db.createConnection();
mycon.Open();

SqlCommand mycmd=new SqlCommand();
mycmd.Connection=mycon;
mycmd.CommandText="updata votedetails set votenum=votenum+1 where voteid="+voteid+" and votedetailsid="+this.rbtnitems.SelectedValue.ToString();
mycmd.ExecuteNonQuery();
mycon.Close();



db.createConnection db是什么对象啊?