จะคำนวนจำนวนวันที่เหลือจากวันที่ยังไงครับ รบกวนช่วยหน่อยครับ VB.Net

Imports System.Data
Imports System.Data.SqlClient
Public Class UploadImage
    Inherits System.Web.UI.Page

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

    Protected Sub ShowDataInfo()

        Dim objConn As SqlConnection
        Dim strConnString As String
        Dim strSQL As StringBuilder
        Dim objCmd As SqlCommand
        Dim dtReader As SqlDataReader

        '*** Open Connection ***'
        strConnString = "Data Source=WDB-PR0168\SQLEXPRESS;Initial Catalog=ESD_001;Integrated Security=True"
        objConn = New SqlConnection
        objConn.ConnectionString = strConnString
        objConn.Open()

        '*** Get Data ***'
        strSQL = New StringBuilder
        strSQL.Append(" SELECT * FROM Tools_ESD ")
        strSQL.Append(" WHERE WD_Tag = @sWD_Tag ")
        objCmd = New SqlCommand(strSQL.ToString(), objConn)
        objCmd.Parameters.Add("@sWD_Tag", SqlDbType.VarChar).Value = TextBox1.Text
        dtReader = objCmd.ExecuteReader()

        If dtReader.HasRows Then
            dtReader.Read()
            Me.lblName.Text = dtReader("Eqiument").ToString()
            Me.lblTag.Text = dtReader("WD_Tag").ToString()
            Me.lblDue.Text = dtReader("Due_Date").ToString()
        End If
        dtReader.Close()
        objConn.Close()
        objConn = Nothing

    End Sub

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