Php – How to check if a value already exists to avoid duplicates

mysqlphpsql

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?

Best Solution

If you don't want to have duplicates you can do following:

If multiple users can insert data to DB, method suggested by @Jeremy Ruten, can lead to an error: after you performed a check someone can insert similar data to the table.