Just before the actual question, I have found some sites showing how to do this but they were using the old mysql method. I am looking for a PDO method.
So I am trying to update an MySQL row (only one column) using PHP and html. All I have is an variable that points to the column I want:
$about = DB::query('SELECT about FROM users WHERE username=:username',
array(':username'=>$_GET['username']))[0]['about'];
And I want to have an with textarea and a button that are updating the row.