Backing up wp tables in test environment

Hello,

I’ve come up with the following function:

function resetdatabase($tablename,$backup_tablename) {
    global $wpdb;
    //$tablename='wp_posts';

	print 'Resetting '.$tablename.' from '.$backup_tablename;

//  drop table if exists
$sql = "DROP TABLE IF_EXISTS '$tablename'";
print $sql;
$wpdb->query($sql);

//die(var_dump($e));

 $e = $wpdb->query("CREATE TABLE $tablename LIKE $backup_tablename");
 var_dump($e);
 $e = $wpdb->query("INSERT INTO $tablename SELECT * FROM $backup_tablename");
 var_dump($e);

I have created backup tables in the wordpress database called posts1 and postmeta1, using phpmyadmin. However the tables wp_posts and wp_postmeta are not being dropped, even though I have granted all privileges to the wordpress user in phpmyadmin. The output is as follows:

Resetting wp_posts from posts1DROP TABLE IF_EXISTS ‘wp_posts’

boolean false

boolean false

does anyone know why I can’t drop the tables?

Thanks,

KC