http://stackoverflow.i2p/questions/72566525/mysql2error-all-parts-of-a-primary-key-must-be-not-null
StandardError: An error has occurred, all later migrations canceled: Mysql2::Error: All parts of a PRIMARY KEY must be NOT NULL; if you need NULL in a key, use UNIQUE instead: CREATE TABLE `books` (`id` int(11) DEFAULT NULL auto_increment PRIMARY KEY, `Book Title` varchar(255), `Author` varchar(255), `Date Published` date, `Book ID` int(11), `Checked Out?