请前辈们帮我看一下我写的简单程序为什么只能执行查询,不能更新
<%@   Page   language= "C# "   Debug=True   %>  
  <%@   Import   Namespace= "System.Data "   %>  
  <%@   Import   Namespace= "System.Data.OleDb "   %>    
  <Script   Language= "C# "   Runat= "Server ">  
 	OleDbConnection   MyConn; 
 public   void   Page_Load(Object   src,EventArgs   e) 
 { 
 	//数据连接字符串 
 	string   MyConnString= "Provider=Microsoft.Jet.OLEDB.4.0;Data   Source= "+Server.MapPath( ". ")+ "..\\RENSHI.MDB; ";              	 
 	MyConn=new   OleDbConnection(MyConnString); 
 	MyConn.Open(); 
 	if(!Page.IsPostBack) 
 	{ 
 		//将数据绑定至Orign数据表格 
 		BindGrid(Orign); 
 	}	 
 }   
 public   void   btnUpdate_Click(Object   sender,EventArgs   e) 
 {	 
 	//更新语句 
             string   strUpdate   =    "UPDATE   department   SET   department.part_pho= 'jjjj ' "; 
             OleDbCommand   MyComm   =   new   OleDbCommand(strUpdate,   MyConn); 
             //执行更新语句 
             MyComm.ExecuteNonQuery();                   
             //MyComm.ExecuteReader(); 
 	//数据绑定至New数据表格 
             //BindGrid(New);               
 }   
 public   void   BindGrid(DataGrid   dg) 
 { 
 	OleDbDataReader   dr; 
 	string   strSel= "Select   *   from   department "; 
 	OleDbCommand   MyComm=new   OleDbCommand(strSel,MyConn);   
 	//注意下面 
 	dr=MyComm.ExecuteReader(); 
 	dg.DataSource=dr; 
 	dg.DataBind(); 
 }              
  </Script>  
  <HTML>  
  <HEAD>  
  <TITLE> MyUpData </TITLE>  
  </HEAD>  
  <BODY>  
  <form   id   = "form1 "   runat= "server ">  
  <CENTER>  
  <TABLE>  
  <TR>  
 	 <TD> 原始数据 </TD>  
 	 <TD> 更新后数据 </TD>  
  </TR>  
  <TR>  
 	 <TD>  <asp:DataGrid   id= "Orign "   runat= "server "   AutoGenerateColumns= "False ">  
 		 <Columns>  
 			 <asp:BoundColumn   HeaderText= "ID "   DataField= "part_id "/>  
 			 <asp:BoundColumn   HeaderText= "电话 "   DataField= "part_pho "/>  
 			 <asp:BoundColumn   HeaderText= "负责人 "   DataField= "principal "/>  
 		 </Columns>  
 		 </asp:DataGrid>  
 	 </TD>  
 	 <TD>  <asp:DataGrid   id= "New "   runat= "server "   AutoGenerateColumns= "False ">  
 		 <Columns>  
 			 <asp:BoundColumn   HeaderText= "ID "   DataField= "part_id "/>  
 			 <asp:BoundColumn   HeaderText= "电话 "   DataField= "part_pho "/>  
 			 <asp:BoundColumn   HeaderText= "负责人 "   DataField= "principal "/>  
 		 </Columns>  
 		 </asp:DataGrid>  
 	 </TD>  
  </TR>  
  <TR>  
 	 <TD>  
                    <asp:Button   id= "btnUpdate "   text= "更新 "   OnClick= "btnUpdate_Click "   runat= "server "/>  
 	 </TD>