php - WordPress 'post_name' in posts table duplicated

I'm trying to receive all portfolio entries from the database. I want to list this and also link the WordPress path to it. This is the SQL query:

SELECT id, post_title, post_name FROM 1bncopo2_posts WHERE post_type='portfolio';
Copy code

post_title could be the following:

1. Mercedes-Benz AMG C63
2. Mercedes-Benz S500
3. BMW 650i XDrive

and now post_name for the first entry of the above list ismercedes-benz-amg-c63. However, I found that in my database table, multiple portfolio vehicles (even vehicles by BMW, etc.) havepost_name set tomercedes-benz-amg-c63. My idea was to generate the URL to the portfolio item usingpost_name as an appendix to the wordpress path. TO BE CLEAR: This is going to be a seperate application reading from the WordPress installation's database and trying to make up the corresponding links to the portfolio items.

Now thatpost_name is notUNIQUE or something I could use, I have two questions:

1. Why would the WP database allow for duplicatedpost_names?
2. How can I get the post (portfolio)'s URL, if not bypost_name?