.Net(c#) 连接 ACCESS 数据库

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

namespace DataAccess
{
    public class DataBasic
    {
        private string cnStr; 
        private OleDbConnection cn;

        public DataBasic()
        {
            cnStr = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + Environment.CurrentDirectory + "/????.mdb;Jet OLEDB:Database Password='????'";  
            cn = null;
        }

        ~DataBasic()
        {
            try
            {
                if (cn != null)
                {
                    cn.Close();
                    cn.Dispose();
                }
            }
            catch { }
            finally
            {
                cn.Close();
                cn.Dispose();
            }
        }
        //打开数据库连接
        protected void Open()
        {
            if (cn == null)
            {
                cn = new OleDbConnection(cnStr);
            }
            if (cn.State == System.Data.ConnectionState.Closed)
            {
                cn.Open();
            }
        }
        //关闭数据库连接
        protected void Close()
        {
            if (cn != null) 
            {
                cn.Close();
            }
        }
        //执行命令操作，以sql字符串为参数传递
        public void Execute(string sql)
        {
            this.Open();
            OleDbCommand cmd = new OleDbCommand(sql,cn);
            cmd.ExecuteNonQuery();
            this.Close();
        }
        //返回数据集
        public DataSet GetDataSet(string sql)
        {
            this.Open();
            OleDbCommand cmd = new OleDbCommand(sql,cn);
            OleDbDataAdapter adapter = new OleDbDataAdapter();
            adapter.SelectCommand = cmd;
            DataSet dataset = new DataSet();
            adapter.Fill(dataset);
            this.Close();
            return dataset;
        }
    }
}