Notes

DELIMITER ;;
CREATE PROCEDURE `withdraw`(
_user_id INT,
_currency varchar(20),
_volume DOUBLE,
_status VARCHAR(255),
_txid VARCHAR(255),
_external_fee DOUBLE,
_etc VARCHAR(255)
)
Return_label:
BEGIN

DECLARE wallet_id INT;
DECLARE wallet_volume DOUBLE;

DECLARE EXIT HANDLER FOR SQLEXCEPTION
BEGIN
ROLLBACK;
END;

SET AUTOCOMMIT = 0;

START TRANSACTION;

/*SET SQL_SAFE_UPDATES = 0;*/

SELECT `id`, `volume` INTO wallet_id, wallet_volume FROM `wallet` WHERE `user_id` = _user_id AND `currency` = _currency;

IF wallet_volume < _volume THEN
SELECT 'You do not have enough money';
COMMIT;
SET AUTOCOMMIT = 1;
LEAVE Return_label;
END IF;

UPDATE `transaction` SET `etc` = _txid, `external_fee` = _external_fee, `status` = _status WHERE `etc` = _etc;

UPDATE `wallet` SET `volume` = round(wallet_volume - _volume, 8) WHERE `id` = wallet_id;

COMMIT;
SET AUTOCOMMIT = 1;

END ;;
DELIMITER ;