function __construct(\DB\SQL $db, $table, $fields = NULL, $ttl = 60)
{
$this->db = $db;
$this->engine = $db->driver();
if ($this->engine == 'oci') {
$table = strtoupper($table);
}
$this->source = $table;
$this->table = $this->db->quotekey($table);
$this->fields = $db->schema($table, $fields, $ttl);
$this->reset();
}