public class AccessDBHelper
    {
        protected static OleDbConnection conn = new OleDbConnection();
        protected static OleDbCommand comm = new OleDbCommand();
        string connStr = ConfigurationManager.AppSettings["filepath"];
        public AccessDBHelper()
        {
            //init
        }
        /**/
        /// <summary>
        /// 打开数据库
        /// </summary>
     private static void openConnection(string path)
        {
            if (conn.State == ConnectionState.Closed)
            {
                conn.ConnectionString = @"Provider=Microsoft.Jet.OleDb.4.0;Data Source=" +                         path;//web.config文件里设定。
                comm.Connection = conn;
                try
                {
        conn.Open();
                }
                catch (Exception e)
                { throw new Exception(e.Message); }
            }
        }
        /**/
        /// <summary>
        /// 关闭数据库
        /// </summary>
 private static void closeConnection()
        {
            if (conn.State == ConnectionState.Open)
            {
                conn.Close();
                conn.Dispose();
                comm.Dispose();
            }
        }
/**/
        /// <summary>
        /// 执行sql语句
        /// </summary>
        /// <param name="sqlstr"></param>
public static void excuteSql(string sqlstr, string path)
        {
            try
            {
                openConnection(path);
                comm.CommandType = CommandType.Text;
                comm.CommandText = sqlstr;
                comm.ExecuteNonQuery();
            }
            catch (Exception e)
            {
                throw new Exception(e.Message);
            }
            finally
            { closeConnection(); }
        }
 /**/
        /// <summary>
        /// 返回指定sql语句的OleDbDataReader对象，使用时请注意关闭这个对象。
        /// </summary>
        /// <param name="sqlstr"></param>
        /// <returns></returns>
        public static OleDbDataReader dataReader(string sqlstr, string path)
        {
            OleDbDataReader dr = null;
            try
            {
openConnection(path);
                comm.CommandText = sqlstr;
                comm.CommandType = CommandType.Text;
                dr = comm.ExecuteReader(CommandBehavior.CloseConnection);
            }
            catch
            {
                try
                {
                    dr.Close();
                    closeConnection();
                }
                catch { }
            }
            return dr;
        }
/**/
        /// <summary>
        /// 返回指定sql语句的OleDbDataReader对象,使用时请注意关闭
        /// </summary>
        /// <param name="sqlstr"></param>
        /// <param name="dr"></param>
        public static void dataReader(string sqlstr, ref OleDbDataReader dr, string path)
        {
            try
            {
openConnection(path);
                comm.CommandText = sqlstr;
                comm.CommandType = CommandType.Text;
                dr = comm.ExecuteReader(CommandBehavior.CloseConnection);
            }
            catch
            {
                try
                {
                    if (dr != null && !dr.IsClosed)
                        dr.Close();
                }
                catch
                {
                }
finally
                {
                    closeConnection();
                }
            }
        }
        /**/
        /// <summary>
        /// 返回指定sql语句的dataset
        /// </summary>
        /// <param name="sqlstr"></param>
        /// <returns></returns>
        public static DataSet dataSet(string sqlstr, string path)
        {
            DataSet ds = new DataSet();
 OleDbDataAdapter da = new OleDbDataAdapter();
            try
            {
                openConnection(path);
                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;
        }
        /**/
        /// <summary>
        /// 返回指定sql语句的dataset
        /// </summary>
        /// <param name="sqlstr"></param>
        /// <param name="ds"></param>
        public static void dataSet(string sqlstr, ref DataSet ds, string path)
        {

OleDbDataAdapter da = new OleDbDataAdapter();
            try
            {
                openConnection(path);
                comm.CommandType = CommandType.Text;
                comm.CommandText = sqlstr;
                da.SelectCommand = comm;
                da.Fill(ds);
            }
            catch (Exception e)
            {
                throw new Exception(e.Message);
            }
finally
            {
                closeConnection();
            }
        }
        /**/
        /// <summary>
        /// 返回指定sql语句的datatable
        /// </summary>
        /// <param name="sqlstr"></param>
        /// <returns></returns>

public static DataTable dataTable(string sqlstr, string path)
        {
            DataTable dt = new DataTable();
            OleDbDataAdapter da = new OleDbDataAdapter();
            try
            {
                openConnection(path);
                comm.CommandType = CommandType.Text;
                comm.CommandText = sqlstr;
                da.SelectCommand = comm;
                da.Fill(dt);
            }
catch (Exception e)
            {
                throw new Exception(e.Message);
            }
            finally
            {
                closeConnection();
            }
            return dt;
        }
        /**/
        /// <summary>
/// 返回指定sql语句的datatable
        /// </summary>
        /// <param name="sqlstr"></param>
        /// <param name="dt"></param>
        public static void dataTable(string sqlstr, ref DataTable dt, string path)
        {
OleDbDataAdapter da = new OleDbDataAdapter();
            try
            {
                openConnection(path);
                comm.CommandType = CommandType.Text;
                comm.CommandText = sqlstr;
                da.SelectCommand = comm;
                da.Fill(dt);
            }
            catch (Exception e)
            {
                throw new Exception(e.Message);
            }
 finally
            {
                closeConnection();
            }
        }
        /**/
        /// <summary>
        /// 返回指定sql语句的dataview
        /// </summary>
        /// <param name="sqlstr"></param>
        /// <returns></returns>

public static DataView dataView(string sqlstr, string path)
        {
            OleDbDataAdapter da = new OleDbDataAdapter();
            DataView dv = new DataView();
            DataSet ds = new DataSet();
            try
            {
                openConnection(path);
                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;
        }

    }