Transcation in asp.net C#

  SqlTransaction tr;
con.Open();
  string save1 = "insert into table(userid,worktime,date) values('" + Session["id"].ToString() + "','" + System.DateTime.Now.ToString() + "','"+dtn1+"')";
                SqlCommand com1 = new SqlCommand(save1, con);
 tr = con.BeginTransaction();
                com1.Transaction = tr;
 com1.ExecuteNonQuery();
   tr.Commit();
                con.Close();
 catch (Exception ex)
            {
                tr.Rollback();
}