Call to undefined function mysql_query() with Login [duplicate]

Answer 1

You are mixing the deprecated mysql extension with mysqli.

Try something like:

$sql = mysqli_query($success, "SELECT * FROM login WHERE username = '".$_POST['username']."' and password = '".md5($_POST['password'])."'");
$row = mysqli_num_rows($sql);

Answer 2

You are mixing mysql and mysqli

Change these lines:

$sql = mysql_query("SELECT * FROM login WHERE username = '".$_POST['username']."' and password = '".md5($_POST['password'])."'");
$row = mysql_num_rows($sql);

to

$sql = mysqli_query($success, "SELECT * FROM login WHERE username = '".$_POST['username']."' and password = '".md5($_POST['password'])."'");
$row = mysqli_num_rows($sql);

Answer 3

What is your PHP version? Extension "Mysql" was deprecated in PHP 5.5.0. Use extension Mysqli (like mysqli_query).

Answer 4

I would recommend that start using mysqli_() and stop using mysql_()

Check the following page: LINK

Warning This extension was deprecated in PHP 5.5.0, and it was removed in PHP 7.0.0. Instead, the MySQLi or PDO_MySQL extension should be used. See also MySQL: choosing an API guide and related FAQ for more information. Alternatives to this function include: mysqli_affected_rows() PDOStatement::rowCount()

Try and use mysqli_() Or PDO