C# 回滚

 private void save_db(){
    SqlConnection conn = new SqlConnection(ConfigurationSettings.AppSettings[""].ToString());
    SqlCommand comm = new SqlCommand();
    conn.Open();
    SqlTransaction rollbk2= conn.BeginTransaction();
    comm.Connection=conn;
    comm.Transaction=rollbk2;
    try
    {
    for(i){
    comm.CommandText="insert into ";
    comm.ExecuteNonQuery();
    }
    rollbk2.Commit();
    }
    catch(Exception exp)
    {
    rollbk2.Rollback();
    Response.Write("save_fail");
    return;
    }
    finally
    {
    conn.Close();
    }
    Response.Write("save_ok");
    }