代码：

using System;using System.Data;using System.Configuration;using System.Data.OleDb;using ahwildlife.Utils;/// 
/// AccessHelper 的摘要说明/// 
public class AccessHelper{    #region 变量    protected static OleDbConnection conn = new OleDbConnection();    protected static OleDbCommand comm = new OleDbCommand();    protected static string connectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=ahwildlife.mdb;Persist Security Info=False;Jet OLEDB:Database Password=sa;";    #endregion    #region 构造函数    /// 
    /// 构造函数    /// 
    public AccessHelper()    {    }    #endregion    #region 打开数据库    /// 
    /// 打开数据库    /// 
    private static void openConnection()    {        if (conn.State == ConnectionState.Closed)        {            conn.ConnectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=ahwildlife.mdb;Persist Security Info=False;Jet OLEDB:Database Password=sa;";            comm.Connection = conn;            try            {                conn.Open();            }            catch (Exception ex)            {                throw new Exception(ex.Message);            }        }    }    #endregion    #region 关闭数据库    /// 
    /// 关闭数据库    /// 
    private static void closeConnection()    {        if (conn.State == ConnectionState.Open)        {            conn.Close();            conn.Dispose();            comm.Dispose();        }    }    #endregion    #region 执行sql语句    /// 
    /// 执行sql语句    /// 
    public static void ExecuteSql(string sqlstr)    {        try        {            openConnection();            comm.CommandType = CommandType.Text;            comm.CommandText = sqlstr;            comm.ExecuteNonQuery();        }        catch (Exception ex)        {            throw new Exception(ex.Message);        }        finally        {            closeConnection();        }    }    #endregion    #region 返回指定sql语句的OleDbDataReader对象,使用时请注意关闭这个对象。    /// 
    /// 返回指定sql语句的OleDbDataReader对象,使用时请注意关闭这个对象。    /// 
    public static OleDbDataReader DataReader(string sqlstr)    {        OleDbDataReader dr = null;        try        {            openConnection();            comm.CommandText = sqlstr;            comm.CommandType = CommandType.Text;            dr = comm.ExecuteReader(CommandBehavior.CloseConnection);        }        catch        {            try            {                dr.Close();                closeConnection();            }            catch { }        }        return dr;    }    #endregion    #region 返回指定sql语句的OleDbDataReader对象,使用时请注意关闭    /// 
    /// 返回指定sql语句的OleDbDataReader对象,使用时请注意关闭    /// 
    public static void DataReader(string sqlstr, ref OleDbDataReader dr)    {        try        {            openConnection();            comm.CommandText = sqlstr;            comm.CommandType = CommandType.Text;            dr = comm.ExecuteReader(CommandBehavior.CloseConnection);        }        catch        {            try            {                if (dr != null && !dr.IsClosed)                    dr.Close();            }            catch            {            }            finally            {                closeConnection();            }        }    }    #endregion    #region 返回指定sql语句的DataSet    /// 
    /// 返回指定sql语句的DataSet    /// 
    ///     /// 
          public static DataSet DataSet(string sqlstr)    {        DataSet ds = new DataSet();        OleDbDataAdapter da = new OleDbDataAdapter();        try        {            openConnection();            comm.CommandType = CommandType.Text;            comm.CommandText = sqlstr;            da.SelectCommand = comm;            da.Fill(ds);        }        catch (Exception e)        {            throw new Exception(e.Message);        }        finally        {            closeConnection();        }        return ds;    }    #endregion    #region 返回指定sql语句的DataSet    /// 
    /// 返回指定sql语句的DataSet    /// 
    ///     ///     public static void DataSet(string sqlstr, ref DataSet ds)    {        OleDbDataAdapter da = new OleDbDataAdapter();        try        {            openConnection();            comm.CommandType = CommandType.Text;            comm.CommandText = sqlstr;            da.SelectCommand = comm;            da.Fill(ds);        }        catch (Exception e)        {            throw new Exception(e.Message);        }        finally        {            closeConnection();        }    }    #endregion    #region 返回指定sql语句的DataTable    /// 
    /// 返回指定sql语句的DataTable    /// 
    ///     /// 
          public static DataTable DataTable(string sqlstr)    {        DataTable dt = Common.GetDataTableCache(sqlstr);//读缓存        if (dt != null)        {            return dt.Copy();        }        else        {            dt = new DataTable();            OleDbDataAdapter da = new OleDbDataAdapter();            try            {                using (OleDbConnection conn = new OleDbConnection())                {                    conn.ConnectionString = connectionString;                    conn.Open();                    using (OleDbCommand comm = new OleDbCommand())                    {                        comm.Connection = conn;                        comm.CommandType = CommandType.Text;                        comm.CommandText = sqlstr;                        da.SelectCommand = comm;                        da.Fill(dt);                    }                }            }            catch (Exception e)            {                throw new Exception(e.Message);            }            finally            {                closeConnection();            }            Common.InsertDataTableCache(sqlstr, dt);//添加缓存            return dt.Copy();        }    }    #endregion    #region 返回指定sql语句的DataTable    /// 
    /// 返回指定sql语句的DataTable    /// 
    public static void DataTable(string sqlstr, ref DataTable dt)    {        OleDbDataAdapter da = new OleDbDataAdapter();        try        {            openConnection();            comm.CommandType = CommandType.Text;            comm.CommandText = sqlstr;            da.SelectCommand = comm;            da.Fill(dt);        }        catch (Exception e)        {            throw new Exception(e.Message);        }        finally        {            closeConnection();        }    }    #endregion    #region 返回指定sql语句的DataView    /// 
    /// 返回指定sql语句的DataView    /// 
    ///     /// 
          public static DataView DataView(string sqlstr)    {        OleDbDataAdapter da = new OleDbDataAdapter();        DataView dv = new DataView();        DataSet ds = new DataSet();        try        {            openConnection();            comm.CommandType = CommandType.Text;            comm.CommandText = sqlstr;            da.SelectCommand = comm;            da.Fill(ds);            dv = ds.Tables[0].DefaultView;        }        catch (Exception e)        {            throw new Exception(e.Message);        }        finally        {            closeConnection();        }        return dv;    }    #endregion}