MySQL/MariaDB equation to null isn't working - mysql

Question

I have database with scheme:
CREATE TABLE `pages` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`title` varchar(255) CHARACTER SET utf8 COLLATE utf8_bin DEFAULT NULL,
`descr` blob,
`updated` binary(14) NOT NULL,
`weight` float NOT NULL,
`s1` varchar(1024) DEFAULT NULL,
`s2` varchar(1024) DEFAULT NULL,
`s3` varchar(1024) DEFAULT NULL,
`s4` varchar(1024) DEFAULT NULL,
`s5` varchar(1024) DEFAULT NULL,
`s6` varchar(1024) DEFAULT NULL,
`s7` varchar(1024) DEFAULT NULL,
`s8` varchar(1024) DEFAULT NULL,
`s9` varchar(1024) DEFAULT NULL,
`s10` varchar(1024) DEFAULT NULL,
`s11` varchar(1024) DEFAULT NULL,
`s12` varchar(1024) DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `page_title` (`title`),
KEY `page_updated` (`updated`)
) ENGINE=InnoDB AUTO_INCREMENT=16074 DEFAULT CHARSET=utf8
Then, I have above 10.000 entries like this:
| 3 | !1 | NULL | 20160412095518 | 0 | NULL | NULL | NULL | ["redirect","1111"] | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL |
But:
> select * from pages where pages.s1 = null limit 5;
Empty set (0.05 sec)
Selection with "pages.s1 like '[%' " working, btw
Why?

Answer 1

NULL is never =, or <>, or >= or <= to anything, even itself.
It's a bit strange that way. But when you get used to it, it makes sense. NULL has no value at all.
You need where pages.s1 IS NULL not = NULL.
(This can be very confusing in Oracle where a zero-length varchar2 string is considered NULL. But it works in a more straightforward way on MySQL.)