php - multiple commands on mysqli query doesn't work?

if I write a query like this :

$conn = new mysqli($db_host, $db_username, $db_password, $db_database);
$conn -> query ("
        DROP TABLE IF EXISTS for_search;
        CREATE TABLE IF NOT EXISTS for_search
        (
          id INT,
          for_search TEXT
        );

");
$conn -> close();

it doesn't work but if i rewrite that like this:

$conn = new mysqli($db_host, $db_username, $db_password, $db_database);
$conn -> query ("
        DROP TABLE IF EXISTS for_search;
");    

$conn -> query ("
        CREATE TABLE IF NOT EXISTS for_search
        (
          id INT,
          for_search TEXT
        );
");
$conn -> close();

it will work!
i want to know why i can't write multiple line queries in mysqli?