To make it more friendly, I would suggest the following:

1. For each URL, instead of having (just) an id, try to add keywords to the URL as well. The earlier the better: /bmw/12345/show_ad.php
2. For each page, make sure you have a good <title>. I.e. My page - Ads - BMW
3. Have a proper <h1>-tag containing the keywords you want to rank high in.

If your pages are dynamic and share a layout, there is a good chance Google will throw many of them out as duplicates. If the content is significantly different from page to page,there is less of a chance of that happening. Google will likely not index all of your pages in either case.

If possible, you should make your urls have words not numbers as Google will look at the URL for keywords.

I would recommend this book. An answer on stack overflow won t give you sufficient information.

(The art of SEO "Theory in Practice")

http://www.amazon.com/dp/0596518862

Yes, it will help a lot, google will still spider pages with parameters on the end, but they still treat .htm pages differently.

As another suggestion, try putting the subject into the filename:

http://www.mypage.com/traeger-grill-for-sale.htm

Or something like that, and have a search parameter thrown in to show_ad.php. This will help even more.

Don t use ids, use the tag in the URL, more Google and human friendly, so instead of

http://www.mypage.com/12345.htm

use URLs like this one

http://www.mypage.com/your_tag_name.htm

To do this type of things you would need another field in you DB for the URL friendly name for the tag (spaces, accents... removed) and use mod_rewrite to rewrite the URLs.

1.URL is primary in your situation. Google does not like URL created from data base. So make a change to it. I recommend you make your URL in this way: www.yourdomain.com/BMW/12456/bmw-car-AD.The advantages of this URL are: It is user friendly, Google friendly(since it contains keywords)and system stable as well(see the ID).

2.All of SEO stuff like good title and description tag,<im> your keywords, decently use <t>,keywords etc. It is worthwhile to read some related articles. Do not obsessed by SEO, do things Google encouraged you to do.

3.Good sitemap is also useful. Pay attention to URL structure of your whole site, if possible, please build some inbound links to your site, that is also helpful.

Good luck to you!

Here is what Google says as of today (20 Apr 2023):

Optimize your site for search engines (for beginners)

Top tips to improve your site s search results on Google Here are a few simple ideas that can help Google understand your site, and help the right people find it.

Be descriptive: Use accurate, descriptive titles for your pages. We recommend putting different topics, products, or services on different pages, one topic (or closely related set of items) per page. Be complete: Mention everything that you have to offer. Google is smart, but we can t guess what you don t tell us.

Be topical: Update your content to account for seasons, trends, or new offerings. For example, if you run an ice cream store that also sells hot chocolate, be sure to feature your ice cream in the summer, and your hot chocolate (or coffee, or sandwiches) prominently in the winter, when people won t be looking for ice cream stores. If a new trend starts for kiwi ice cream and you have it in your store, feature it prominently.

Keep your site up to date: If you haven t updated your site since 1925, it s time to remove the references to Calvin Coolidge in your current events blog.

Use text: Don t put all your site content or page titles only in images, video, or other non-text formats that Google understands less well than text. If you use a graphic for your site name, include the name in the page text as well.

Get referrals: Have your site mentioned in useful places online. See if you can get into your local online news sites, or in any other appropriate resources.

Want more? Read the full guide here.