in gridview there are 2 dropdown 2 dropdown is dependent on first.

Question

After selecting the ddlprogram it should display the ddl_Location where the programs are avaliable

aspx file

 <asp:GridView ID="gvProgram" runat="server" DataKeyNames="ChoiceName" AutoGenerateColumns="False" OnRowDataBound="gvProgram_RowDataBound" Width="100%" BackColor="White" BorderColor="#CCCCCC" BorderStyle="None" BorderWidth="1px" CellPadding="3">
     <Columns>
         <asp:BoundField DataField="ChoiceName" HeaderText="Choice" ItemStyle-Width="20%" />
         <asp:TemplateField HeaderText="Program">
             <ItemTemplate>
                 <asp:DropDownList ID="ddlProgram" runat="server" class="form-control form-control-sm  mb-9" OnSelectedIndexChanged="ddlProgram_SelectedIndexChanged" AutoPostBack="true">
                     <asp:ListItem Value="0">Select Program</asp:ListItem>

                 </asp:DropDownList>
                 <asp:RequiredFieldValidator ID="rfvddlProgram" runat="server" ErrorMessage="*" ControlToValidate="ddlProgram" Font-Bold="False" Font-Names="Verdana" Font-Size="8pt"
                     SetFocusOnError="True" ValidationGroup="v1" ForeColor="Red" InitialValue="0"></asp:RequiredFieldValidator>
                
             </ItemTemplate>
         </asp:TemplateField>
         <asp:TemplateField HeaderText="Location">
             <ItemTemplate>
                 <asp:DropDownList ID="ddl_Location" runat="server" class="form-control form-control-sm  mb-9">
                     <asp:ListItem Value="0">Select Location</asp:ListItem>

                 </asp:DropDownList>
                 <asp:RequiredFieldValidator ID="rfvddlLocation" runat="server" ErrorMessage="*" ControlToValidate="ddl_Location" Font-Bold="False" Font-Names="Verdana" Font-Size="8pt"
                     SetFocusOnError="True" ValidationGroup="v1" ForeColor="Red" InitialValue="0"></asp:RequiredFieldValidator>
             </ItemTemplate>
         </asp:TemplateField>
     </Columns>
     <FooterStyle BackColor="White" ForeColor="#000066" />
     <HeaderStyle BackColor="#6777ef" Font-Bold="True" ForeColor="White" />
     <PagerStyle BackColor="White" ForeColor="#000066" HorizontalAlign="Left" />
     <RowStyle ForeColor="#000066" />
     <SelectedRowStyle BackColor="#669999" Font-Bold="True" ForeColor="White" />
     <SortedAscendingCellStyle BackColor="#F1F1F1" />
     <SortedAscendingHeaderStyle BackColor="#007DBB" />
     <SortedDescendingCellStyle BackColor="#CAC9C9" />
     <SortedDescendingHeaderStyle BackColor="#00547E" />
 </asp:GridView>

aspx.cs 

 

 protected void gvProgram_RowDataBound(object sender, GridViewRowEventArgs e)
 {
     DataSet ds = new DataSet();
     Btech.Mode = "BindData";
     ds = objDal.Adm(Btech);

     if (e.Row.RowType == DataControlRowType.DataRow)
     {
         if (ds.Tables[0].Rows.Count > 0 && ds.Tables[1].Rows.Count > 0)
         {
             DropDownList ddlProgram = (DropDownList)e.Row.FindControl("ddlProgram");
             ddlProgram.Items.Clear();
             ddlProgram.DataSource = ds.Tables[13];
             ddlProgram.DataTextField = "Description";
             ddlProgram.DataValueField = "CourseID";
             ddlProgram.DataBind();
             ddlProgram.Items.Insert(0, new ListItem("Select course", "0"));

             DropDownList ddl_Location = (DropDownList)e.Row.FindControl("ddl_Location");
             //ddlTeacherNames.Items.Clear();
             ddl_Location.DataSource = ds.Tables[14];
             ddl_Location.DataTextField = "CenterName";
             ddl_Location.DataValueField = "CentreCode";
             ddl_Location.DataBind();
             ddl_Location.Items.Insert(0, new ListItem("Select Location", "0"));
         }
     }

 }

 

protected void ddlProgram_SelectedIndexChanged(object sender, EventArgs e)
{

}