Displaying Gridview on Index Change Event of Dropdownlist

Database Design

Query

create table tbl_student(Student_ID int identity(1,1),
StudentName varchar(80),RollNo int,Class varchar(50),
Section varchar(50))

Design

Now I am creating a Webform to insert some data to the database.
 
Dropdownindex.aspx:



Dropdownindex.aspx.cs:

protected void Button1_Click(object sender, EventArgs e)
{
    try
    {
        string str = "Data Source=.;Initial Catalog=Wordpress;Integrated Security=True";
        SqlConnection con = new SqlConnection(str);
        SqlCommand cmd = new SqlCommand("insert into tbl_student ([StudentName],[RollNo],[Class],[Section]) values (@StudentName,@RollNo,@Class,@Section)", con);
        con.Open();
        cmd.Parameters.AddWithValue("@StudentName", TextBox1.Text);
        cmd.Parameters.AddWithValue("@RollNo", TextBox2.Text);
        cmd.Parameters.AddWithValue("@Class", DropDownList1.Text);
        cmd.Parameters.AddWithValue("@Section", DropDownList2.Text);
        cmd.ExecuteNonQuery();
        Label5.Text = "Submitted Successfully";
        con.Close();
    }
    catch(Exception ex)
    {
        throw ex;
    }

}

Output:



Now create a Webform for Displaying the GridView on the Index change event of dropdownlist.
 
DropdownGrid.aspx:

Code:

Here I am hardcoding the dropdown list items:

<asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="true" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged">
      <asp:ListItem>--Select--</asp:ListItem>
      <asp:ListItem Value="UKG">UKG</asp:ListItem>
      <asp:ListItem Value="I ">I </asp:ListItem>
      <asp:ListItem Value="II ">II</asp:ListItem>
      <asp:ListItem Value="III ">III</asp:ListItem>
      <asp:ListItem Value="IV ">IV </asp:ListItem>
      <asp:ListItem Value="V ">V</asp:ListItem>
      <asp:ListItem Value="VI ">VI</asp:ListItem>
      <asp:ListItem Value="VII ">VII</asp:ListItem>
      <asp:ListItem Value="VIII ">VIII</asp:ListItem>
      <asp:ListItem Value="IX ">IX</asp:ListItem>
      <asp:ListItem Value="X ">X</asp:ListItem>
      <asp:ListItem Value="XI ">XI</asp:ListItem>
      <asp:ListItem Value="XII ">XII</asp:ListItem>
</asp:DropDownList>

DropdownGrid.aspx.cs:

Here is the code for displaying the GridView on Index change event of dropdownlist:

protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
    string str = "Data Source=.;Initial Catalog=Wordpress;Integrated Security=True";
    SqlConnection con = new SqlConnection(str);
    con.Open();
    SqlCommand cmd1 = new SqlCommand("Select StudentName,RollNo,Section from tbl_student where Class ='" + DropDownList1.SelectedItem.Text + "'", con);
    SqlDataAdapter da1 = new SqlDataAdapter(cmd1);
    DataSet ds = new DataSet();
    da1.Fill(ds, "tbl_student");
    GridView1.DataMember = "tbl_student";
    GridView1.DataSource = ds;
    GridView1.DataBind();
    con.Close();
}

Output: