How to display data from gridview with the help of dropdownlist

Partial Class listcust
    Inherits System.Web.UI.Page
    Dim objcustmaster As New Clcustmaster
    Dim sSQL As String
    Dim sCOM As New Common
    Protected Sub Button4_Click1(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button4.Click

        objcustmaster = New Clcustmaster
        If DropDownList4.SelectedIndex = 0 Then
            sSQL = objcustmaster.DispDataName(TextBox1.Text)

        ElseIf DropDownList4.SelectedIndex = 1 Then
            sSQL = objcustmaster.DispDataMobile(TextBox1.Text)

        ElseIf DropDownList4.SelectedIndex = 2 Then
            sSQL = objcustmaster.DispDataTeleo(TextBox1.Text)

        ElseIf DropDownList4.SelectedIndex = 3 Then
            sSQL = objcustmaster.DispDataCity(TextBox1.Text)

        ElseIf DropDownList4.SelectedIndex = 4 Then
            sSQL = objcustmaster.DispDataEmail(TextBox1.Text)

        End If

    End Sub

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

        sCOM = New Common
        objcustmaster = New Clcustmaster

        If Not Page.IsPostBack Then
            sSQL = objcustmaster.DispDataName(DropDownList4.Text)

        ElseIf sSQL = objcustmaster.DispDataMobile(DropDownList4.Text) Then

        ElseIf sSQL = objcustmaster.DispDataTeleo(DropDownList4.Text) Then
        ElseIf sSQL = objcustmaster.DispDataCity(DropDownList4.Text) Then
        ElseIf sSQL = objcustmaster.DispDataEmail(DropDownList4.Text) Then

        End If

    End Sub

    Protected Sub GridView1_RowEditing(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewEditEventArgs) Handles GridView1.RowEditing
        Response.Redirect("entrycust.aspx?action=edit&cc=" & GridView1.DataKeys(e.NewEditIndex).Value.ToString())

    End Sub

    Protected Sub GridView1_RowDeleting(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewDeleteEventArgs) Handles GridView1.RowDeleting
    End Sub

    Protected Sub GridView1_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles GridView1.SelectedIndexChanged

    End Sub

    Protected Sub Button3_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button3.Click

    End Sub
End Class