Get a tMySQL field from a PHP variable

Hi guys!

I'm a bit new to PHP and MySQL. I've built a very basic dynamic site but what I want to do is get an entry from the database depending on an ID passed through the URL

For example, when a user goes to "www.mysite.com/hello.php?artid=1" I want to call an entry from the database with the ID of 1

So far I just do it like so:

PHP Code:

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$sql = "SELECT content FROM dynamic_content WHERE id = 1"; 


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This gives me a variable I want for later but I want to remove the last "id = 1" bit with something like "id = artid" but I'm not sure exactly what I'm supposed to write.

I've found some similar articles on the web but haven't managed to find my answer (maybe my terminology is stopping the search engines finding it?)