Normalization: Is it considered compliant to split static, numeric values like a year into their own table?
The other database designer is simply wrong, but your reasoning is wrong as well. Assume you start with this table, which has a single candidate key, "game_title".

Table: game_titles

game_title                      year_first_released
--
The first game                  1998
The second game                 1999
Best game: the third one        2001
The fourth game                 2003
Forty-two, the end of games     2011


You evaluate whether it's in 2NF by asking yourself these questions.

Q: First of all, is it in 1NF?

A: Yes, it is.

Q: What are the prime attributes (attributes that are part of a candidate key)?

A: "game_title" is the only prime attribute.

Q: What are the non-prime attributes?

A: "year_first_released" is the only one.

Q: Is "year_first_released" functionally dependent on the whole of "game_title", or on just a part of it?

A: The sole candidate key, "game_title", is a single column; it doesn't even have parts. So "year_first_released" is functionally dependent on the whole of "game_title".

Voilà. You've found 2NF.

You can cut through some of the formal terms by asking first whether it's in 1NF, and then answering this question.

Q: Are there any composite candidate keys?

A: No.

Voilà. You've found 2NF again.

By definition, for a table to violate 2NF, it has to have at least one candidate key that has more than one column.

Here are your reasons for rejecting your friend's opinion.


A year is just a non-primitive numeric value.
A year is static by its very nature.
A year serves as its own identifier.
A table of years introduces additional maintenance.
A table of years might have extra rows that aren't referenced.
A table of years increases database size.


None of these reasons have anything at all to do with whether a table is in 2NF.

In designing a database, it's not wrong to consider maintenance issues, database size, unreferenced rows, range constraints, and so on. It's just wrong to call those things normalization.

Oh, and that two-column table that I provided above--it's in 5NF.