DropDownList in ASP.NET using VB.NET

For example

Drag and Drop one GridView control, one Button control, one label control and one DropDownList control on the form.

ASPX code

<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>rohatash</asp:ListItem>

            <asp:ListItem>andrew</asp:ListItem>

            <asp:ListItem>yardi</asp:ListItem>

            <asp:ListItem>Rahul</asp:ListItem>

            <asp:ListItem>monu</asp:ListItem>

    </asp:DropDownList>

    &nbsp;&nbsp;&nbsp;<asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>

    &nbsp;&nbsp;&nbsp;&nbsp;

    <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

Now run the application.

Figure1.

Now select username from dropdownlist and click on the ShowRecord Button.

Figure2

Now select an item from the DropDownList which is not in database. GridView will be invisible for that selected item.

Figure3