Trying to check if username already exists in MySQL database using PHP

Question

I\'ve looked at the many other posts that were similar to my issue and implemented their solutions (as far as I can tell) as exactly as I could. However, every time I execut

Answer 1

Try this:

$query = mysql_query("SELECT username FROM Users WHERE username='$username' ")

Don't add $con to mysql_query() function.

Disclaimer: using the username variable in the string passed to mysql_query, as shown above, is a trivial SQL injection attack vector in so far the username depends on parameters of the Web request (query string, headers, request body, etc), or otherwise parameters a malicious entity may control.