SELECT
    id,
    issue,
    delivery,
    proforma,
    restoration,
    deleted,
    IFNULL(delivery, issue) AS DATE,
    totalPrice totalPrice,
    ROUND(totalPrice * (1 - discount / 100), 2) AS discountPrice,
    (SELECT
            SUM(price) SUM
        FROM
            payment
        WHERE
            invoice_id = id
        GROUP BY invoice_id)
FROM
    invoice
WHERE
    deleted = 0 AND user_id = 25
HAVING DATE BETWEEN '2014-05-01' AND '2014-05-31'
ORDER BY issue DESC