gistfile1.aw

<?php

class QueryBuilder implements IteratorAggregate
{
    private $conn;

    private $parts = array();

    public function __construct(Connection $conn)
    {
        $this->conn = $conn;
    }

    public function select($fields)
    {
        $this->parts['select'] = $fields;
    }

    public function from($table)
    {
        $this->parts['from'] = $table;
    }

    public function where($where)
    {
        $this->parts['where'] = $where;
    }

    public function andWhere($where)
    {
        $this->parts['where'] .= ' AND '.$where;
    }

    public function orderBy($field, $dir = 'ASC')
    {
        $this->parts['orderBy'] = "$field $dir";
    }

    public function getSql()
    {
        return $this->parts['select'].' '.
            $this->parts['from'].' '.
            $this->parts['where'].' '.
            $this->parts['orderBy'];
    }

    public function execute()
    {
        $sql = $this->getSql();
        return $this->conn->execute($sql);
    }

    public function getIterator()
    {
        return new ArrayIterator($this->execute());
    }
}