Accidentally specified weird sql query. What happened? - mysql

Question

I ran this sql query in my database:
update payments set method = 'paysafecard' AND amount = 25 WHERE payment_id IN (1,2,3,4,5,...)
Of course i meant set method = 'paysafecard' , amount = 25
However I did it in phpmyadmin and it showed me that rows were affected. After running it again it showed 0 rows affected.
I don't know what may have changed in the database, what could this have done?
My table looks like this:
CREATE TABLE IF NOT EXISTS `payments` (
`payment_id` int(11) NOT NULL AUTO_INCREMENT,
`method_unique_id` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`method` enum('moneybookers','paypal','admin','wallet','voucher','sofortueberweisung','bitcoin','paysafecard','paymentwall') COLLATE utf8_unicode_ci NOT NULL,
`method_tid` int(11) DEFAULT NULL,
`uid` int(11) NOT NULL,
`created_at` timestamp NULL DEFAULT CURRENT_TIMESTAMP,
`plan` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
`expires_at` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
`amount` decimal(8,2) NOT NULL,
`currency` enum('EUR','USD','BTC') COLLATE utf8_unicode_ci NOT NULL,
PRIMARY KEY (`payment_id`),
UNIQUE KEY `method` (`method`,`method_tid`),
UNIQUE KEY `method_unique_id` (`method_unique_id`,`method`),
KEY `expires_at` (`expires_at`),
KEY `uid` (`uid`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci AUTO_INCREMENT=8030 ;
I am running
-- Server version: 5.1.41
-- PHP Version: 5.3.2-1ubuntu4.11

Answer 1

This would result in the method field being set to '0' for all of your records fitting the where clause.
It is interpreted as the following:
set method = ('paysafecard' AND amount = 25)
This is a logical AND, and results in a boolean value for these records(which will be parsed to the corresponding field of your column).