3NF Vs 2NF, which is more strict?
A database in 3NF is in 2NF also.  A simple mnemonic is:


The key
The whole key
and nothing but the key
So help me Codd


2NF states that a table contains no fields that are logically a function of a part of the primary key.  3NF states that a table contains no fields that are logically a function of any field of the table but the 'whole' key.  3NF can be viewed as a specialisation of 2NF.