<link rel="canonical" href="http://www.example.com/category/subcategory/example-product/product-id" />
I have a whole bunch of query string URLs (company products) that I have rewritten to friendly ones (such as that indicated above). At present, seems search engines are still seeing both versions, so I thought perhaps I should add the canonical tag to my preferred URL.
Incredibly, days and days of trolling god-knows-what web development resources on the internet has not clearly answered the question of "how" for me. Hoping someone here can help.
For the record, I am utilizing a single file (products1.php) to populate all of my products.