Make sure url is not repeated
<p>I am building a website where people can submit their blog addresses. What I'm trying to do is that when they submit a blog, for me to check the database to see if it's already in the database.</p>

<p>The problem that I have is that somebody can write the urls as "http://blog.com" or "http://www.blog.com" .</p>

<p>What would be the best way for me to check if the url is repeated? </p>

<p>What I think is I would check if the url has a "http://" and a "www", and check for the part after "www" but I feel this would be slow because I have more than 3000 urls. Thanks!</p>
