Medical Center database
Non primary-foreign key JOINs
Non-equi JOINs
Non-equi self JOINs
Instruction
Good! We can also use non-equi JOINs in order to, for example, list items added after a particular item or date:
SELECT item1.name FROM items item1 JOIN items item2 ON item1.date_added < item2.date_added WHERE item2.id = 3
With this query, we limit the aliased item2 table to only one record (with id = 3) and tell our database to show the names of all items that were added before the item with id = 3.
Exercise
Show the names of all employees who are younger than Mark Gatis.
Stuck? Here's a hint!
Type:
SELECT emp1.name FROM employee emp1 JOIN employee emp2 ON emp1.age < emp2.age WHERE emp2.name = 'Mark Gatis'
