• Hi Tom,

    I was also confused about whether the 3NF example was in 2NF or not.

    I had just submitted a really long question, but then saw your reply to James:

    There's nothing in 2NF to stop an attribute being dependent on some set of attributes that includes something that isn't part of a key. The rule is that if a non-prime attribute is dependent on something that is a subset of a key that subset must be the whole key. Or putting it another way, the whole key is not the only thing it can be dependent on, the rule is simply that it must never be dependent on a partial key.

    This is a great summary, and IMO would be a good addition to the 2NF article.

    Thanks, John