The tutorial .sql file for creating the database has a default set for the ItemGenreID column in the table:
CREATE TABLE `itemgenres` (
`ItemGenreID` int(10) NOT NULL auto_increment,
For some reason your table import didn't take the auto_increment setting when you ran the .sql file to create the database tables. Update that column to be an auto_increment in your database like the tutorial should have done and it should fix this issue.