Thanks Scott and all,

I tried to keep the example simple for the article, but I might take your suggestion a step further and assign the "Is Commission Eligible" indicator to a given position instead of to an employee. And then assign each employee to a position.

In most cases whether or not an employee gets a commission depends on their position (e.g., "Salesperson" might be eligible, while "Janitor" is probably not), and commission eligibility will not necessarily follow an employee from position to position (e.g., Joe transfers from the Sales team to Janitorial Services). You might even want to keep a separate salary/position history for employees, so you can track their job and pay history - but all of this would require additional tables, constraints, etc.  And I really wanted to keep my example as simple as possible for purposes of the article.