Thank you for help, but not working.. I need to retrieve some records if existing in a mysql database table and populate a gridview, which is initially populated with random data.

This is why I included this button on the web page, using CommandArgument (off the gridview).

<asp:ImageButton ID="btnReco"
    ImageUrl="/aspnet/img/recovery_button.gif"
    runat="server"
    OnClick="btnReco_Click"
    CommandArgument="1"
    CssClass="ddl_Class_new"
    Visible="true" />

The dropdownlist from each row of gridview are empty... even if the value stored in the table is OK or KO.

protected void gvProducts_RowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        string Ticket = e.Row.Cells[1].Text;
 
        ImageButton imgBtn = (ImageButton)e.Row.FindControl("btnReco");
 
        if (imgBtn != null)
        {
            //Find the DropDownList in the Row.
            DropDownList ddl1 = (e.Row.FindControl("ddl1") as DropDownList);
            ddl1.DataSource = GetData("SELECT DISTINCT t1 FROM `tb_1` WHERE t1 = '" + Ticket.ToString() + "';");
            ddl1.DataTextField = "t1";
            ddl1.DataValueField = "t1";
            ddl1.DataBind();
 
            //Add Default Item in the DropDownList.
            ddl1.Items.Insert(0, new ListItem("[ === === === ]"));
 
            //Select the Country of Customer in DropDownList.
            string t1 = (e.Row.FindControl("t1") as Label).Text;
            ddl1.Items.FindByValue(t1).Selected = true;
        }
    }
}

<asp:TemplateField
     HeaderText="t1"
     ItemStyle-CssClass="ddl_Class_new"
     ItemStyle-HorizontalAlign="Center">
     <ItemTemplate>
         <asp:Label ID="lbl_ddl1" runat="server" Text='<%# Eval("t1") %>' Visible = "false" />
         <div>
             <asp:DropDownList ID="ddl1" runat="server"
                 AutoPostBack="true"
                 OnSelectedIndexChanged="ddl1_SelectedIndexChanged"
                 BackColor="Yellow"
                 CssClass="ddl_Class_new">
                 <asp:ListItem Text="[ === === === ]" Value=""></asp:ListItem>
                 <asp:ListItem Text="OK" Value="OK"></asp:ListItem>
                 <asp:ListItem Text="KO" Value="KO"></asp:ListItem>
             </asp:DropDownList>
         </div>
     </ItemTemplate>
 </asp:TemplateField>