Get Next GridView row details based on DropDownList selection in ASP.Net

Hi amar,

Check this example. Now please take its reference and correct your code.

HTML

<asp:GridView ID="gvDetails" runat="server" AutoGenerateColumns="false">
    <Columns>
        <asp:BoundField DataField="Id" HeaderText="Id" />
        <asp:BoundField DataField="Name" HeaderText="Name" />
        <asp:TemplateField>
            <ItemTemplate>
                <asp:DropDownList ID="ddlCountries" runat="server" OnSelectedIndexChanged="ddlCountries_SelectedIndexChanged"
                    AutoPostBack="true">
                    <asp:ListItem Text="United States" Value="United States"></asp:ListItem>
                    <asp:ListItem Text="India" Value="India"> </asp:ListItem>
                    <asp:ListItem Text="France" Value="France"></asp:ListItem>
                    <asp:ListItem Text="Russia" Value="Russia"></asp:ListItem>
                </asp:DropDownList>
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>

Namespaces

C#

using System.Data;

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        DataTable dt = new DataTable();
        dt.Columns.AddRange(new DataColumn[3] { new DataColumn("Id", typeof(int)),
                        new DataColumn("Name", typeof(string)),
                        new DataColumn("Country",typeof(string)) });
        dt.Rows.Add(1, "John Hammond", "United States");
        dt.Rows.Add(2, "Mudassar Khan", "India");
        dt.Rows.Add(3, "Suzanne Mathews", "France");
        dt.Rows.Add(4, "Robert Schidner", "Russia");
        gvDetails.DataSource = dt;
        gvDetails.DataBind();
    }
}

protected void ddlCountries_SelectedIndexChanged(object sender, EventArgs e)
{
    DropDownList ddl = sender as DropDownList;
    int index = (ddl.NamingContainer as GridViewRow).RowIndex;

    if (index < gvDetails.Rows.Count - 1)
    {
        GridViewRow nextRow = gvDetails.Rows[index + 1];
        string id = nextRow.Cells[0].Text;
        string name = nextRow.Cells[1].Text;
        string country = (nextRow.FindControl("ddlCountries") as DropDownList).SelectedValue;
        ClientScript.RegisterStartupScript(this.GetType(), "alert", "alert('ID: " + id + "\\nName: " + name + "\\nCountry: " + country + "');", true);
    }
}

Screenshot