Just use ANSI style joins. You're guaranteed never to accidentally do a cartesian join.

For example:
Normal join - "SELECT * FROM table1 t1 JOIN table2 t2 ON (t1.column = t2.column)"
Cartesian join - "SELECT * FROM table1 t1 CROSS JOIN table2 t2"

Big difference, no mistakes no matter how many tables/columns you're pulling in to your query.