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CREATE TABLE IF NOT EXISTS `testtable1` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`key_boolean` tinyint NULL DEFAULT NULL,
PRIMARY KEY (`id`)
) AUTO_INCREMENT=1;
INSERT INTO `testtable1` (`key_boolean`) VALUES (1);
INSERT INTO `testtable1` () VALUES ();
SELECT *,
key_boolean = 1,
NOT (key_boolean = 1),
key_boolean <=> 1,
NOT (key_boolean <=> 1)
FROM testtable1;
| id | key_boolean | key_boolean = 1 | NOT (key_boolean = 1) | key_boolean <=> 1 | NOT (key_boolean <=> 1) |
|---|---|---|---|---|---|
| 1 | 1 | 1 | 0 | 1 | 0 |
| 2 | null | null | null | 0 | 1 |