<asp:SqlDataSource ID="SDDiplAll" runat="server" 
                ConnectionString="<%$ ConnectionStrings:WEBConnectionString %>" 
                
                SelectCommand="SELECT [IdDipl], [IdWorker], [IdSchool], [NameDipl], [NomDipl], [DatDipl], [pk], [DataF] FROM [Diploma] WHERE ([IdWorker] = @IdWorker)" 
                
                InsertCommand="INSERT INTO Diploma(IdWorker, IdSchool, NameDipl, NameCourse, NomDipl, DatDipl, Dat1, Dat2, Price, pk, DataF) VALUES (@IdWorker, @IdSchool, @NameDipl, @NameCourse, @NomDipl, @DatDipl, @Dat1, @Dat2, @Price, @pk, @DataF" 
                DeleteCommand="DELETE FROM Diploma WHERE (IdDipl = @IdDipl)" 
                onselecting="SDDiplAll_Selecting">
                <DeleteParameters>
                    <asp:ControlParameter ControlID="FormView2" Name="IdDipl" 
                        PropertyName="SelectedValue" />
                </DeleteParameters>
                <InsertParameters>
                    <asp:ControlParameter ControlID="FormView2" Name="IdWorker" 
                        PropertyName="SelectedValue" />
                    <asp:Parameter Name="IdSchool" />
                    <asp:Parameter Name="NameDipl" />
                    <asp:Parameter Name="NameCourse" />
                    <asp:Parameter Name="NomDipl" />
                    <asp:Parameter Name="DatDipl" />
                    <asp:Parameter Name="Dat1" />
                    <asp:Parameter Name="Dat2" />
                    <asp:Parameter Name="Price" />
                    <asp:Parameter Name="pk" />
                    <asp:Parameter Name="DataF" />
                </InsertParameters>
                <SelectParameters>
                    <asp:ControlParameter ControlID="FormView2" DefaultValue="0" Name="IdWorker" 
                        PropertyName="SelectedValue" Type="Int32" />
                </SelectParameters>
            </asp:SqlDataSource>

DropDownList ddl2 = FormView2.FindControl("DropDownList2") as DropDownList;

            SDDiplAll.SelectParameters["IdWorker"].DefaultValue = ddl2.SelectedValue.ToString();
            SDDiplAll.DataBind();

protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)
        {

            DropDownList ddl2 = FormView2.FindControl("DropDownList2") as DropDownList;
            SDDiplAll.SelectParameters["IdWorker"].DefaultValue = ddl2.SelectedValue.ToString();
            SDDiplAll.DataBind();
     
            SDEditDiplom.SelectCommand = "SELECT [IdDipl], [IdSchool], [IdWorker], [NameDipl], [NameCourse], [NomDipl], [DatDipl], [Dat1], [Dat2], [Price], [pk], [DataF] FROM [Diploma] WHERE [IdDipl] =  " + Convert.ToInt32(GridView1.SelectedDataKey["IdDipl"]);
            SDEditDiplom.DataBind();
            
           Session["sWorker"] = Convert.ToString(GridView1.SelectedDataKey["IdWorker"]);
           Session["sDipl"] = Convert.ToString(GridView1.SelectedDataKey["IdDipl"]);

           if (FormView2.CurrentMode == FormViewMode.Insert)
           { this.FormView2.ChangeMode(FormViewMode.Edit); }
        }