连接不同数据OleDb(不完整)

using System;
using System.Data;
using System.Data.OleDb;

namespace ASPNETClassLibrary
{
 /// <summary>
 /// Command_OLEDB 的摘要说明。
 /// </summary>
 public  class Command_OLEDB
 {
  public  Command_OLEDB()
  {
  }

  #region

  /// <summary>
  /// 连接数据字段
  /// </summary>
  private static string _connectionString;
  /// <summary>
  /// 设置为只读
  /// </summary>
  public static  string connectionString
  {
   get
   {
    return _connectionString;
   }
   set
   {
    _connectionString = value;
   }
  }
  /// <summary>
  /// 打开数据的连接
  /// </summary>
  /// <returns></returns>
  public static OleDbConnection getOleDbConnection()
  {
   try
   {
    string oledbString = _connectionString ; //"Provider=Microsoft.Jet.OLEDB.4.0;User ID=Admin;Data Source='" + HttpContext.Current.Server.MapPath("~/LHB_DataBase/LHB.mdb") + "';Jet OLEDB:Engine Type=5;Jet OLEDB:Database Locking Mode=1;Jet OLEDB:Global Partial Bulk Ops=2;Jet OLEDB:Global Bulk Transactions=1;Jet OLEDB:Create System Database=False;Jet OLEDB:Encrypt Database=False;Jet OLEDB:Don't Copy Locale on Compact=False;Jet OLEDB:Compact Without Replica Repair=False;Jet OLEDB:SFP=False";
    OleDbConnection oc = new OleDbConnection(oledbString);
    oc.Open();
    return oc;
   }
   catch(Exception ex)
   {
    string temp = ex.Message;
    return null;
   }
  }
 

  /// <summary>
  /// 获取 OleDbCommand 对象
  /// </summary>
  /// <returns></returns>
  public static OleDbCommand getOleDbCommand()
  {
   OleDbConnection cn =  getOleDbConnection();
   if (cn == null)
   {
    return null;
   }
   else
   {
    OleDbCommand cmd = new OleDbCommand();
    cmd.Connection = cn;
    return cmd;
   }
  }

  /// <summary>
  /// 新建一个DataSet对象
  /// </summary>
  /// <param name="ExecuteString">要执行的语句,可是Sql语句,也可是存储过程的名称</param>
  /// <returns></returns>
  public static DataSet getDataSet(string ExecuteString)
  {
   OleDbConnection cn =  getOleDbConnection();
   OleDbDataAdapter odda = new OleDbDataAdapter(ExecuteString,cn);
   DataSet ds = new DataSet();
   if (cn == null)
   {
    return null;
   }
   else
   {
    odda.Fill(ds);
    return ds;
   }
  }

  /// <summary>
  /// 新建一个DataSet对象
  /// </summary>
  /// <param name="ExecuteString">要执行的语句,可是Sql语句,也可是存储过程的名称</param>
  /// <param name="name">表的名字</param>
  /// <returns></returns>
  public static DataSet getDataSet(string ExecuteString, string name)
  {
   OleDbConnection cn =  getOleDbConnection();
   OleDbDataAdapter odda = new OleDbDataAdapter(ExecuteString,cn);
   DataSet ds = new DataSet();
   if (cn == null)
   {
    return null;
   }
   else
   {
    odda.Fill(ds,name);
    return ds;
   }

  }

 
  /// <summary>
  /// 新建一个DataSet对象
  /// </summary>
  /// <param name="ExecuteString">要执行的语句,可是Sql语句,也可是存储过程的名称</param>
  /// <returns></returns>
  public static DataTable getDataTable(string ExecuteString)
  {
   OleDbConnection cn =  getOleDbConnection();
   OleDbDataAdapter odda = new OleDbDataAdapter(ExecuteString,cn);
   DataTable dt = new DataTable();
   if (cn == null)
   {
    return null;
   }
   else
   {
    odda.Fill(dt);
    return dt;
   }

  }

  /// <summary>
  /// 执行SQL语句,返回受影响的行数，
  /// -2 说明数据连接失败，
  /// -3 发生异常错误。
  /// </summary>
  /// <param name="ExecuteString">要执行的语句,可是Sql语句,也可是存储过程的名称</param>
  /// <returns></returns>
  public static int ExecuteNonQuery(string ExecuteString)
  {
   int count;
   OleDbCommand cmd =  getOleDbCommand();
   if (cmd == null)
   {
    /// <summary>
    /// 说明数据连接失败
    /// <summary>
    return -2;
   }
   else
   {
    /// <summary>
    /// 把要执行的字符串给LHB_CMD
    /// <summary>
    cmd.CommandText = ExecuteString;
    /// <summary>
    /// 开始执行
    /// <summary>
    count = cmd.ExecuteNonQuery();
    /// <summary>
    /// 返回一个值.
    /// <summary>       
    return count;
   }
  }

  
  /// <summary>
  /// 执行指定的Sql语句，返回首行首列
  ///  -2 说明数据连接失败，
  ///  -3 发生异常错误。
  /// </summary>
  /// <param name="ExecuteString">要执行的语句,可是Sql语句,也可是存储过程的名称</param>
  /// <returns>返回首行首列的那个值</returns>
  public static string ExecuteScalar(string ExecuteString)
  {
   try
   {
    string ShouHangShouLie;
    OleDbCommand cmd =  getOleDbCommand();
    if (cmd == null)
    {
     return "-2";
    }
    else
    {
     cmd.CommandText = ExecuteString;
     ShouHangShouLie = cmd.ExecuteScalar().ToString();
     return ShouHangShouLie;
    }
   }
   catch (Exception LHB_EE)
   {
    string temp = LHB_EE.Message;
    return "-3";
   }
  }

 
  #endregion
 }
}