conn.Open();
            object firstObj = comm.ExecuteScalar();
            comm.Dispose();
            conn.Close();

            return firstObj;
        }

        public static object ExecuteScalar(string connStr, CommandType commandType, string commStr, params SqlParameter[] commandParameters)
        ...{
            SqlConnection conn = new SqlConnection(connStr);
            SqlCommand comm = new SqlCommand(commStr, conn);
            comm.CommandType = commandType;

            for (int i = 0; i < commandParameters.Length; i++)
                comm.Parameters.Add(commandParameters[i]);

            conn.Open();
            object firstObj = comm.ExecuteScalar();
            comm.Dispose();
            conn.Close();

            return firstObj;
        }
        #endregion

        ExecuteReader的两个重载#region ExecuteReader的两个重载
        public static SqlDataReader ExecuteReader(string connStr, CommandType commandType, string commStr)
        ...{
            SqlConnection conn = new SqlConnection(connStr);
            SqlCommand comm = new SqlCommand(commStr, conn);
            comm.CommandType = commandType;

            conn.Open();
            SqlDataReader reader = comm.ExecuteReader(CommandBehavior.CloseConnection);