I assume that you have a link in your view with labsn dropdown. Then you can use a little of jquery to change the href of your link.
1) Define your link to redirect to another action that accepts labsn
<a href="#" id="labsnAnchor">Go</a>
2) Hook up to the dropdown list change event in jquery and in the handler change href according to the selected value. This javascript has to be embedded in the view because it uses @Url.Action helper.
$('#ddllab').onchange(function(){
val selectedValue = $(this).val();
var link = $('#labsnAnchor');
link.attr('href', '@Url.Action("LabInfo", "YourController")' + '?labsn=' + selectedValue );
});
3) Create an action in your controller that will accept labsn.
public ActionResult LabInfo(int labsn)
{
...
}
EDIT
If you want a delete functionality then I would recommend to use a FORM and a Post action on the server side.
1) You can create a form in your view with a hidden value that will contain labsn and a submit button
@using(Html.BeginForm('DeleteLab', 'YourController')
{
<input type="hidden" value="LabsnToDelete"/>
<input type="submit" value="Delete"/>
}
2) Modify the hidden value using same javascript as for the anchor
$('#ddllab').onchange(function(){
val selectedValue = $(this).val();
var link = $('#labsnAnchor');
link.attr('href', '@Url.Action("LabInfo", "YourController")' + '?labsn=' + selectedValue );
$('#LabsnToDelete').val(selectedValue); // just add this line to set LabsnToDelete value
});
3) And create a controller action that will accept post requests to delete labs
public ActionResult DeleteLab(int labsnToDelete)
{
...
}