A functional dependency α→β is called a partial dependency if there is a proper subset γ of such that α γ→ β. We say that is partially dependent on α. A relation schema R is in second normal form (2NF) if each attribute A in R meets one of the following criteria:
• It appears in a candidate key.
• It is not partially dependent on a candidate key.
Show that every 3NF schema is in 2NF. (Hint: Show that every partial dependency is a transitive dependency.)