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databasedatabase-designprimary-keydatabase-normalizationfirst-normal-form

reasoning that creating a primary key satisfies the first normal form

I am studying for the Microsoft Technology Exam and one of the practice questions is:

Creating a primary key satisfies the first normal form. True or False?

It seems False because first normal form is rid of duplicate groups. But the text (Database Fundamentals, Exam 98-364 by Microsoft Press) says:

The first normalized form (1NF) means the data is in an entity format, which basically means that the following three conditions must be met:
• The table must have no duplicate records. Once you have defined a primary key for the table, you have met the first normalized form criterion.

What is wrong with my reasoning?

Solution

  • A primary key must be completely unique. So once this is part of a record, it is distinct from any other record.

    eg.

    Record 1
---------
KEY = 1
Name = Fred Boggs
Age = 84


Record 2
--------
KEY = 2
Name = Fred Boggs
Age = 84

    These 2 records are different because the field KEY is different. Therefore although the rest of the data is the same, it meets the requirements for 1NF.