Primary keys - the basics
Single-column primary keys
Multicolumn primary keys
Auto-increment columns and sequences
Instruction
Great! As you could see, each id was indeed unique and they were generally speaking consecutive numbers. One number was missing (7), but nothing particular happens. You will, however, discover soon enough that no two rows can share the same value in the primary key column.
Exercise
Okay, let's add a movie with id 7 so that there is no gap in numbering. Its title is Titanic and it was produced in 1997.
Stuck? Here's a hint!
Type
INSERT INTO movie VALUES (7, 'Titanic', 1997);
