重构sqlconnection/sqlcommand/sqldatareader/datatable

            if (conn.State == ConnectionState.Closed)
            {
                conn.Open();
            }
            return conn;
        }
        public int ExecuteNonQuery(string sql)
        {
            int res;
            try
            {
                cmd = new SqlCommand(sql, GetConn());
                cmd.CommandTimeout = 60;
                res = cmd.ExecuteNonQuery();
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                if (conn.State == ConnectionState.Open)
                {
                    conn.Close();
                }
            }
            return res;
        }
        public DataTable ExecuteQuery(string sql)
        {

            try
            {
                dt = new DataTable();
                cmd = new SqlCommand(sql, GetConn());
                rd = cmd.ExecuteReader();
                dt.Load(rd);
               rd.Close();
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                if (conn.State == ConnectionState.Open)
                {
                    conn.Close();
                }
            }
            return dt;
        }
    }
}