Model.class.php

<?php

class Model {

    protected static function db(){
        return DatabasePDO::singleton();
    }

    // *** Queries in sql/model.sql.php ****
    protected static $requests = array();

    public static function addSqlQuery($key, $sql){
        static::$requests[$key] = $sql;
    }

    public static function sqlQueryNamed($key){
        return static::$requests[$key];
    }

    protected static function query($sql){
        $st = static::db()->query($sql)  or die("sql query error ! request : " . $sql);
        $st->setFetchMode(PDO::FETCH_CLASS | PDO::FETCH_PROPS_LATE, get_called_class());
        return $st;
    }

    protected static function exec($sqlKey,$values=array()){
        $sth = static::db()->prepare(static::sqlQueryNamed($sqlKey));
        $sth->setFetchMode(PDO::FETCH_CLASS | PDO::FETCH_PROPS_LATE, get_called_class());
        $sth->execute($values);
        return $sth;
    }
}