<?php

namespace Database;

/**
 * Description of PDO
 * @author stump
 */

trait PDO 
{
    private $pdo;
    private $statement;

    private $DB_HOST = '127.0.0.1';
    private $DB_NAME = 'mydb';
    private $DB_USER = 'root';
    private $DB_PW = '1111';
    
    public function __get( $name )
    {
        echo $name;
        return $this -> $name;
    }
    
    public function connect()
    {
        $this -> pdo = new \PDO(
                "mysql:host=" . $this -> DB_HOST . " ;dbname=" . $this -> DB_NAME . ";", 
                $this -> DB_USER, 
                $this -> DB_PW
            );
         $this -> pdo;
    }
    
    public function prepare( $sql )
    {
        return ( TRUE == ( $this -> statement = $this -> pdo -> prepare( $sql ) ) );
    }
    
    public function execute( $param )
    {
        return ( TRUE == $this -> statement -> execute( $param ) );
    }
    
    public function fetch()
    {
        return $this -> statement -> fetchAll( \PDO::FETCH_CLASS );
    }
}

<?php

namespace Database;
use Database\QueryBuilder,
    Database\PDO;

/**
 * Description of User
 * @author stump
 */
class Database
{
    use PDO
    {
        prepare as pdo_prepare;
        execute as pdo_execute;
    }
    
    public $sql = NULL;
    public $param = [];
            
    public function __construct()
    {
        $this -> connect();
    }
    
    public function Build( QueryBuilder $Query )
    {
        $this -> sql = empty( $Query -> apply() ) 
                        ? ""
                        : $Query -> sql;
        return ( bool )$this -> sql;
    }
    
    public function execute()
    {
        $this -> pdo_prepare( $this -> sql );
        $execute = $this -> pdo_execute( $this -> param );
        return $execute;
    }
    
    public function query()
    {    
        
        $this -> pdo_prepare( $this -> sql );
        $this -> pdo_execute( $this -> param );
        $fetch = $this -> fetch();
        return $fetch;
    }
}

$Query = new QueryBuilder();
$Query -> addpart( 'SELECT', "*" )
            -> addpart( 'FROM', 'user' )
            -> addpart( 'WHERE', ['id > 1', 'id < 10'] )
            -> addpart( 'LIMIT', [8] );

$db = new Database();
$db -> Build( $Query );
$res = $db -> query();
//левой-правой-повторить