Hey guys,
Its been a while since I posted, and I know just how fantastic this community is, so Im hopeful that someone here will be able to give me some advice with this canonical tag question that I have.
It seems I have a Google indexing issue which is causing me some concern.
Im using custom built blogging software (written in PHP) that posts articles (or pages) in the following format.
/articles_view_article.php?articleID=41
Each article uses the same page, just a differnent ID tag. No big deal.
/articles_view_article.php?articleID=41
/articles_view_article.php?articleID=42
/articles_view_article.php?articleID=43
etc etc…
So the following page…
/articles_view_article.php?articleID=41
…once rewritten using the URL rewrite method is then displayed as a search friendly URL as such…
/blog/41/How-to-Ask-For-Help-With-Canonical-Tags-On-Sitepoint.php
Okay thats all fine, however BOTH pages are being indexed.
/articles_view_article.php?articleID=41
/blog/41/How-to-Ask-For-Help-With-Canonical-Tags-On-Sitepoint.php
In an attempt to prevent this, I added the following code to my robots.txt file…
Disallow: /articles_view_article.php?
However that has seemed to only worsen the problem, as Im now finding pages that are showing as “UNTITLED” within Googles index.
These untitled pages point to the same page…
So now it seems I have 3 variations!
Untitled
/articles_view_article.php?articleID=41
/blog/41/How-to-Ask-For-Help-With-Canonical-Tags-On-Sitepoint.php
My question is this…
If each article or “page” uses the same /articles_view_article.php page then how on earth do I add my canonical tag to each of them to specify their uniqueness?
Any help would be very much appreciated. 
Cheers,
John