Cyclic addition in mysql how?

Question

PHP

There is a code:

$a = $_POST['colums'];
    if($a != null){
      for ($i = 1, $i<$a; $i++){	
        $query = "ALTER TABLE maps ADD days_'$i' VARCHAR(100)";
        mysql_query($query);
      }
    }

the cycle is working but ALTER TABLE does not want to add and does not show an error (the code was removed for an error)

Answer 1

$query = "ALTER TABLE maps ADD days_".$i." VARCHAR(100)"