title: possible to convert string to GUID?
body: <p>I have a dropdownlist selection, selected value will be ID, type is GUID, currently my code for the select button is </p>
  
  <pre><code>Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
  
      Dim Selection As String = Nothing
  
      If Not DropDownList3.SelectedValue Is Nothing Then Selection = DropDownList3.SelectedValue
  
      Session("Selected") = Selection
  
  End Sub
  </code></pre>
  
  <p>then I have </p>
  
  <pre><code>Dim ID is guid
  ID = Session("Selected")
  </code></pre>
  
  <p>then i need to execute sql such as <code>select * from .. where ID=..</code>
  Problem happens at <code>ID = Session("Selected")</code>, as <code>ID</code> is <code>GUID</code>, while <code>Session("Selected")</code> is <code>string</code>
  I wonder if there is a way to handle it?
  Thanks very much for help!</p>