'Column 'Category' in where clause is ambiguos' breaks my page

I was trying to make products_search.php work and I broke products_results.php. I get the following error when I enter a known Category 'Boulders' at http://outofchaos.net/gsc/www/products_search.php and when I use the Products dropdown - http://outofchaos.net/gsc/www/products_results.php?Category_ID=6
When I uploaded products_search.php to my testing server, I clicked 'yes' to move dependent files. Now my products_results.php on my testing server when accessed thru the dropdown menu is giving me the same 'Column 'Category' in where clause is ambiguous' message. I restored the working file but still same problem. I did not upload dependent files to the remote/live site but I did just upload products_search.php by itself to see how it acted there and same thing! dropdown product/category search still is broken there. http://outofchaos.net/gsc/www/products_results.php?Category_ID=6 . I'm hoping the answer to the error for search will allow me to fix whatever is screwing up products_results. Couldn't see what else could have changed in that I only uploaded products_search to live server to muck up the product_results page.Help please.

Try updating line 21 to:

$WADbSearch1->addComparisonFromEdit("category.Category","Category","AND","Includes",0);

Since you have a column named Category in your products table as well as your categories table it can't determine which table you are trying to search.

In reality you should consider removing the Category column from your products table entirely, since you have a CategoryID column you join on it will be enough to get the category name from your categories table and it is a good idea to not store redundant data like that.

I'd also suggest in the future to make sure your column names are unique even across tables. That way you won't have to worry about ambiguous column names in your query moving forward.

Now this is interesting. I made no changes as I was finished for day when I got your reply above.The following strange behaviors occur:
1> I checked the site 1st thing and http://outofchaos.net/gsc/www/products_results.php?Category_ID=6 came up fine on both testing and remote servers.
2> However, when I did a Search using products_search.php, I got 'No Results.'
3> Then when I went back and tried http://outofchaos.net/gsc/www/products_results.php?Category_ID=6 again, I get 'No Results'
4> I Go back to Search and enter Category - 'Boulders' - still get 'No Results' but now http://outofchaos.net/gsc/www/products_results.php?Category_ID=6 which is 'Boulders' works again but 'Gardenrock bags' which is http://outofchaos.net/gsc/www/products_results.php?Category_ID=32 does not - gives me 'No Results'
5> I go back to Search and enter Category - 'Gardenrock Bags' - - still get 'No Results' but now http://outofchaos.net/gsc/www/products_results.php?Category_ID=32 which is 'Gardenrock Bags'' works again but 'Boulders which is http://outofchaos.net/gsc/www/products_results.php?Category_ID=6 does not now - gives me 'No Results'
6> I made the Code change you suggested and still get same results above.
7> I removed 'Category' from the Products table and it totally broke the pages so I put it back
Looks like the act of using products_search is caching something that negatively affects using the Products dropdown to select Categories via products_results.php
Any clues here that might suggest a solution to you?
FYI - I removed products_results.php from my live server as I have an interested party reviewing the Product pages and I can't afford to have it behaving irratically. But I attach the latest products_search.php here if it helps.

Can you upload a copy of the broken pages (rename them so they won't interfere with your site). And then I'll need FTP information to fully debug them.

See private message.