Convert relative url to fully qualified url in YQL

Question

I've got an index page with link to other pages that have content.

select href from html where url="http://.../" and xpath='//a[@class="index"]'

The resulting values of href are in the form of "/sub/page/../"

Now, i want to fetch data from all all hrefs. Something like

select * from html where url in (select href from html where url="http://.../" and xpath='//a[@class="index"]')

However it fails because href is not fully qualified.

Is there a way around it?