protected function setValue($key, $value, $expire)
{
$expire = $expire <= 0 ? 0 : time() + $expire;
$sql = 'REPLACE INTO ' . self::CACHE_TABLE . ' VALUES(\'' . $key . '\',\'' . sqlite_escape_string(serialize($value)) . '\',' . $expire . ')';
return $this->_db->query($sql) !== false;
}