15 zadacha

CREATE PROCEDURE usp_transfer_money(from_account_id INT, to_account_id INT, amount DECIMAL(19,4))
BEGIN
    START TRANSACTION;
        UPDATE accounts SET balance = balance - amount
            WHERE id = from_account_id;
            UPDATE accounts SET balance = balance + amount
            WHERE id = to_account_id;

        IF((SELECT COUNT(*) FROM accounts
              WHERE id = from_account_id) <> 1)
           THEN ROLLBACK;
        ELSEIF(amount > (SELECT balance FROM accounts WHERE id = from_account_id))
            THEN ROLLBACK;
        ELSEIF(amount <= 0)
            THEN ROLLBACK;
        ELSEIF((SELECT balance FROM accounts WHERE id = from_account_id) <= 0)
            THEN ROLLBACK;
        ELSEIF((SELECT COUNT(*) FROM accounts
              WHERE id = to_account_id) <> 1)
           THEN ROLLBACK;
        ELSEIF(amount <= 0)
            THEN ROLLBACK;
        ELSEIF(from_account_id = to_account_id)
            THEN ROLLBACK;
        ELSE
            COMMIT;
        END IF;

END