DBHelper类,我喜欢用的感觉比较清晰

直接传入SQL语句的DBHelper类

   //数据连接
       public static readonly string connectionString = ConfigurationManager.ConnectionStrings      ["connectionString"].ConnectionString;
   //执行增删改操作
        public static int ExcuteNonQuery(string sql)
        {
            using (SqlConnection conn = new SqlConnection(connectionString))
            {
                SqlCommand comand = new SqlCommand(sql, conn);

                if (conn.State != ConnectionState.Open)
                    conn.Open();
                int val = comand.ExecuteNonQuery();
                return val;
            }
        }
        //执行查询操作
        public static SqlDataReader ExcuteReader(string sql)
        {
            SqlConnection conn = new SqlConnection(connectionString);
            if (conn.State != ConnectionState.Open)
                conn.Open();
            SqlCommand comand = new SqlCommand(sql, conn);
            return comand.ExecuteReader();

        }

可传入SQL语句或存储过程的DBHelper类

 

/// <summary>
        /// 连接字符串
        /// </summary>
        public static readonly string ConnectionString = ConfigurationManager.ConnectionStrings["connectionString"].ConnectionString;

        /// <summary>
        /// 执行SQL 命令
        /// (用于添加、修改、删除操作)
        /// </summary>
        /// <param name="connectionString">连接字符串</param>
        /// <param name="command">SQL命令对象</param>
        /// <returns>返回受影响行数</returns>
        public static int ExecuteNonQuery(string connectionString, SqlCommand command)
        {
            try
            {
                using (SqlConnection conn = new SqlConnection(connectionString))
                {
                    command.Connection = conn;
                    if (conn.State != ConnectionState.Open)
                        conn.Open();
                    int val = command.ExecuteNonQuery();
                    return val;
                }
            }
            catch (Exception ex)
            {
                throw new ApplicationException("ExecuteNonQuery发生错误!", ex);
            }

        }

        /// <summary>
        /// 执行SQL命令返回Reader对象
        /// （用于查询操作）
        /// 注意：在使用完Reader对象后必须关闭它，否则该Reader对象使用的连接不会自动关闭！
        /// </summary>
        /// <param name="connectionString">连接字符串</param>
        /// <param name="command">命令对象</param>
        /// <returns>返回查询得到的Reader对象</returns>
        public static SqlDataReader ExecuteReader(string connectionString, SqlCommand command)
        {
            SqlConnection conn = new SqlConnection(connectionString);
            try
            {
                command.Connection = conn;

                if (conn.State != ConnectionState.Open)
                    conn.Open();
                SqlDataReader rdr = command.ExecuteReader(CommandBehavior.CloseConnection);
                return rdr;
            }
            catch (Exception ex)
            {
                conn.Close();
                throw new ApplicationException("ExecuteReader发生错误!", ex);
            }
        }