C#--带参SQL语句数通用数据访问类

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;

namespace DAL.Helper
{
    public class SQLHelper
    {
        private static string connString =
            ConfigurationManager.ConnectionStrings["sqlConnString"].ToString();       

        #region 执行带参数SQL语句
        /// <summary>
        /// 执行增、删、改 Sql(Update、insert、delete)方法
        /// </summary>
        /// <param name="sql">提交的SQL语句，可以根据需要添加参数</param>
        /// <param name="param">参数数组（如果没有参数，请传递null）</param>
        /// <returns>返回受影响行数</returns>
        public static int Update(string sql,SqlParameter[] param)
        {
            SqlConnection conn = new SqlConnection(connString);
            SqlCommand cmd = new SqlCommand(sql, conn);
            if(param != null)
            {
                cmd.Parameters.AddRange(param);//添加参数组
            }
            try
            {
                conn.Open();
                return cmd.ExecuteNonQuery();
            }
            catch (Exception ex)
            {
                string info = "执行public static int Update";
                info += "(string sql,SqlParameter[] param)"+ex.Message;
                throw new Exception(info);
            }
            finally
            {
                conn.Close();
            }           
        }
        /// <summary>
        /// 执行单一结果集查询
        /// </summary>
        /// <param name="sql">提交SQL语句，可根据需要添加参数</param>
        /// <param name="param">参数数组，（如果没有参数、传递null）</param>
        /// <returns>返回object对象</returns>
        public static object GetSingleResult(string sql, SqlParameter[] param)
        {
            SqlConnection conn = new SqlConnection(connString);
            SqlCommand cmd = new SqlCommand(sql, conn);
            if(param != null)
            {
                cmd.Parameters.AddRange(param);//添加参数组；
            }
            try
            {
                conn.Open();
                return cmd.ExecuteScalar();
            }
            catch (Exception ex)
            {
                string info = "执行public static object GetSingleResult";
                info += "(string sql, SqlParameter[] param)" + ex.Message;
                throw new Exception(info);
            }
            finally
            {
                conn.Close();
            }
        }
        /// <summary>
        /// 返回全部结果集查询
        /// </summary>
        /// <param name="sql"></param>
        /// <param name="param"></param>
        /// <returns></returns>
        public static SqlDataReader GetReader(string sql,SqlParameter[] param)
        {
            SqlConnection conn = new SqlConnection(connString);
            SqlCommand cmd = new SqlCommand(sql, conn);
            if(param != null)
            {
                cmd.Parameters.AddRange(param);//添加参数组；
            }
            try
            {
                conn.Open();
                return cmd.ExecuteReader(CommandBehavior.CloseConnection);
            }
            catch (Exception ex)
            {
                string info = "public static SqlDataReader GetReader";
                    info +="(string sql,SqlParameter[] param)"+ex.Message;
                conn.Close();
                throw new Exception(info);
            }
        }
        #endregion
    }
}