<p>I've got a table of URLs and I don't want any duplicate URLs. How do I check to see if a given URL is already in the table using PHP/MySQL?</p>

You could do this query:
```
```
SELECT url FROM urls WHERE url = 'http://asdf.com' LIMIT 1
```
```
Then check if
mysql_num_rows()
== 1 to see if it exists.