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

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

aspx file

Select Program

SetFocusOnError="True" ValidationGroup="v1" ForeColor="Red" InitialValue="0">

Select Location

SetFocusOnError="True" ValidationGroup="v1" ForeColor="Red" InitialValue="0">

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)
{

}

It seems like you want to populate the ddl_Location dropdown based on the selected value of the ddlProgram dropdown. You can achieve this by fetching the relevant data inside the ddlProgram_SelectedIndexChanged event. Here is a sample code snippet:

protected void ddlProgram_SelectedIndexChanged(object sender, EventArgs e)
{
    // Get the selected program
    DropDownList ddlProgram = (DropDownList)sender;
    string selectedProgram = ddlProgram.SelectedValue;

    // Find the ddl_Location control
    GridViewRow row = (GridViewRow)ddlProgram.NamingContainer;
    DropDownList ddl_Location = (DropDownList)row.FindControl("ddl_Location");

    // Fetch the locations based on the selected program
    // This is just a placeholder, replace it with your actual data fetching logic
    DataSet dsLocations = FetchLocationsForProgram(selectedProgram);

    // Bind the fetched data to ddl_Location
    ddl_Location.DataSource = dsLocations;
    ddl_Location.DataTextField = "CenterName";
    ddl_Location.DataValueField = "CentreCode";
    ddl_Location.DataBind();
    ddl_Location.Items.Insert(0, new ListItem("Select Location", "0"));
}

In this code, FetchLocationsForProgram(selectedProgram) is a placeholder method which you should replace with your actual logic to fetch the locations based on the selected program. This method should return a DataSet or DataTable which can be bound to ddl_Location.

Please replace the placeholder method with your actual data fetching logic.

Thanks.