What a join is (a way of relating two tables together in a query)
What an inner and outer join is
The different types of outer joins (left, right, full)
Some other join types that are available if needed (cross join) or that are not recommended (natural join)
The alternative join syntax (the WHERE clause)
All of the topics so far have only worked with two tables at a time: either the employee and office table, or the employee and sales_meeting ...