请教高手，谁为我比较比较这两段代码

<asp:DropDownList ID="DropDownList1" Runat="server" 
        AppendDataBoundItems="true" 
        AutoPostBack="True"        
        DataSourceID="SqlDataSource2" 
        DataTextField="state" 
        DataValueField="state"> 
      <Items> 
        <asp:ListItem Text="(Choose a state)" Value="" /> ------------
      </Items> 
    </asp:DropDownList> 
    <asp:SqlDataSource ID="SqlDataSource2" Runat="server" 
        SelectCommand="SELECT DISTINCT [state] FROM [authors]" 
        ConnectionString=" <%$ ConnectionStrings:LocalSqlPubs %>"/> --------
    <br /> 
    <br /> 
    <asp:GridView ID="GridView1" Runat="server" 
        DataSourceID="SqlDataSource1" 
        AllowSorting="True" -------
        AutoGenerateColumns="False" 
        AllowPaging="True"> --
      <Columns> 
        <asp:BoundField HeaderText="au_id" DataField="au_id" SortExpression="au_id" /> -----------
        <asp:BoundField HeaderText="au_lname" DataField="au_lname" SortExpression="au_lname" /> 
        <asp:BoundField HeaderText="au_fname" DataField="au_fname" SortExpression="au_fname" /> 
        <asp:BoundField HeaderText="phone" DataField="phone" SortExpression="phone" /> 
        <asp:BoundField HeaderText="address" DataField="address" SortExpression="address" /> 
        <asp:BoundField HeaderText="city" DataField="city" SortExpression="city" /> 
        <asp:BoundField HeaderText="state" DataField="state" SortExpression="state" /> 
        <asp:BoundField HeaderText="zip" DataField="zip" SortExpression="zip" /> 
        <asp:CheckBoxField HeaderText="contract" SortExpression="contract" DataField="contract" /> 
      </Columns> 
    </asp:GridView> 
    
    <asp:SqlDataSource ID="SqlDataSource1"  Runat="server" 
        ConnectionString=' <%$ ConnectionStrings:LocalSqlPubs %>' 
        CancelSelectOnNullParameter="false" 
        SelectCommand=" 
            SELECT * FROM authors 
            WHERE state = IsNull(@state, state)"> ------------
      <SelectParameters> 
        <asp:ControlParameter Name="state" 
            ControlID="DropDownList1" 
            PropertyName="SelectedValue" /> 
      </SelectParameters> 
    </asp:SqlDataSource>不一样的地方有"---------"