クエリの必要はありません。これを実行するだけです
$this->db->table_exists('customer');
例
$query = $this->db->table_exists('customer');
$count = count($query);
if (empty($count)) {
echo "No Table Found";
}
elseif ($count == 1) {
echo "Oopzz! There is table";
}
elseif ($count >1) {
echo "Ohh !! There are many tables";
}