How to insert \n character in MySQL table from PHP form

I am trying a few hours now to add the character \n in a MySQL table. I have a form. If someone presses OK with no data given i want to pass in the table tha character \n.

I have tried this.

$null_value = '\n';
$null_value = mysql_real_escape_string($null_value);
mysql_query("INSERT INTO table (x,x) VALUES ('$null_value','$null_value');

But nothing happened. I would appreciate it if someone can help me out with this ?