/**
* @return ezcQueryExpression
*/
protected function createExpression()
{
if ($this->db instanceof ezcDbInterface) {
$expr = $this->db->createExpression($this->db);
} else {
$driver = $this->db->getAttribute(PDO::ATTR_DRIVER_NAME);
$className = 'ezcQueryExpression';
if ($driver !== 'mysql') {
$className .= strtoupper(substr($impName, 0, 1)) . substr($impName, 1);
}
$expr = new $className($this->db);
}
return $expr;
}
/**
* Constructs a new ezcQuery that works on the database $db and with the aliases $aliases.
*
* The aliases can be used to substitute the column and table names with more
* friendly names. E.g PersistentObject uses it to allow using property and class
* names instead of column and table names.
*
* @param PDO $db
* @param array(string=>string) $aliases
*/
public function __construct(PDO $db, array $aliases = array())
{
$this->db = $db;
if ($this->expr == null) {
$this->expr = $db->createExpression();
}
if (!empty($aliases)) {
$this->aliases = $aliases;
$this->expr->setAliases($this->aliases);
}
}