C# DBHelper

using System;
using System.Collections.Generic;
using System.Text;
using System.Data.OleDb;
using System.Data;

namespace NJCS.Dal
{
    public class DBHelper
    {
        private static OleDbConnection connection;
        public static OleDbConnection Connection
        {
            get
            {
                string connectionString = @“Provider=Microsoft.Jet.OLEDB.4.0;Data Source=web/App_Data/njcs.mdb“;
                if （connection == null）
                {
                    connection = new OleDbConnection（connectionString）;
                    connection.Open（）;
                }
                else if （connection.State == System.Data.ConnectionState.Closed）
                {
                    connection.Open（）;
                }
                else if （connection.State == System.Data.ConnectionState.Broken）
                {
                    connection.Close（）;
                    connection.Open（）;
                }
                return connection;
            }
        }


        public static int ExecuteCommand（string safeSql）
        {
            OleDbCommand cmd = new OleDbCommand（safeSql Connection）;
            int result = cmd.ExecuteNonQuery（）;
            return result;
        }

        public static int ExecuteCommand（string sql params OleDbParameter[] values）
        {
            OleDbCommand cmd = new OleDbCommand（sql Connection）;
            cmd.Parameters.AddRange（values）;
            return cmd.ExecuteNonQuery（）;
        }

        public static int GetScalar（string safeSql）
        {
            OleDbCommand cmd = new OleDbCommand（safeSql Connection）;