How to Bind DropDownList in GridView in asp.NET

<div >

        <asp:GridView ID="GridView1" runat="server" CellPadding="4" ForeColor="#333333"

            GridLines="None">

            <AlternatingRowStyle BackColor="White" />

            <EditRowStyle BackColor="#2461BF" />

            <FooterStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" />

            <HeaderStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" />

            <PagerStyle BackColor="#2461BF" ForeColor="White" HorizontalAlign="Center" />

            <RowStyle BackColor="#EFF3FB" />

            <SelectedRowStyle BackColor="#D1DDF1" Font-Bold="True" ForeColor="#333333" />

            <SortedAscendingCellStyle BackColor="#F5F7FB" />

            <SortedAscendingHeaderStyle BackColor="#6D95E1" />

            <SortedDescendingCellStyle BackColor="#E9EBEF" />

            <SortedDescendingHeaderStyle BackColor="#4870BE" />

        asp:GridView>           

        <br />

        <br /> 

    <asp:DropDownList ID="DropDownList1" runat="server">

            <asp:ListItem>rohatashasp:ListItem>

            <asp:ListItem>andrewasp:ListItem>

            <asp:ListItem>yardiasp:ListItem>

            <asp:ListItem>Rahulasp:ListItem>

            <asp:ListItem>monuasp:ListItem>

    asp:DropDownList>

       <asp:Label ID="Label1" runat="server" Text="Label">asp:Label>

    <br />

    <br />

    <br />

    <asp:Button ID="Button1" runat="server" onclick="Button1_Click" Text="ShowRecord"

        Height="37px" />

    div>

Now double click on the Button Control and add the following code.

Protected Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button1.Click

        Dim str As String = "Data Source=.;uid=sa;pwd=Password$2;database=dropdowndatabase"

        Dim con As New SqlConnection(str)

        con.Open()

        Dim cmd As New SqlCommand("select * from info where username = '" + DropDownList1.SelectedItem.Text + "'", con)

        'Dim cmd As New SqlCommand("select * from info")

        Dim Adpt As New SqlDataAdapter(cmd)

        Dim ds As DataSet = New DataSet()

        If (Adpt.Fill(ds, "info")) Then

            GridView1.DataSource = ds.Tables(0)

            GridView1.DataBind()

            Label1.Text = "Found"

            GridView1.Visible = True

        Else

            Label1.Text = "Not found"

            GridView1.Visible = False

        End If

    End Sub