Question

//code in aspx.

   </asp:TemplateField>
        :
        :
        :
   <ItemTemplate>
   <asp:DropDownList ID="didDdl" runat="server" 
    DataSourceID="departmentsDataSource" 
    DataTextField="Department" 
    DataValueField="DepartmentID" 
    SelectedValue='<%# Bind("DepartmentID") %>' 
    Enabled="False" />
   </ItemTemplate>
   </asp:TemplateField>

Q:I have to insert the selected dropdownlist items to a table all at a once i.e when i click a submit button(which i have not shown here) then all the selected values should go at a time to a table.

Answer 1

My assumption is you are using Gridview. So this will work.

protected void btnSubmit_Click(object sender, EventArgs e)
{
    List<string> lst = new List<string>();

    foreach(GridViewRow gvr in GridView1.Rows)
    {
        if (gvr.RowType == DataControlRowType.DataRow)
        {
            lst.Add(((DropDownList)gvr.FindControl("didDdl")).SelectedValue);
        }
    }
}

Improvised solution

protected void btnSubmit_Click(object sender, EventArgs e)
{

    SqlCommand comm = new SqlCommand();

    StringBuilder sb = new StringBuilder("INSET INTO [Table] ");

    string template = " SELECT @{0} UNION ALL ";


    foreach(GridViewRow gvr in GridView1.Rows)
    {
        if (gvr.RowType == DataControlRowType.DataRow)
        {
            string value = ((DropDownList)gvr.FindControl("didDdl")).SelectedValue;

            sb.AppendFormat(template, value);
            comm.Parameters.Add(new SqlParameter("@" + value, value));

        }
    }
    comm.CommandText = sb.ToString()

}