“A relation is in third normal form if there is no transitive dependency for non-prime attributes (and is also in the second form…)”

Now, here's the definition of the third normal form: So when you go through to compliance with second normal form, you’re reorganizing table relations to make sure that they are fairly independent, in order to achieve this goal. You wouldn’t want to be storing the word “Administrator” in a table of 100 different individual administrators. You want to reference the status once instead, and add that to those 100 user accounts. If that sounds confusing, you can also think about 2NF as an attempt to “reduce redundant data being stored in memory.”įor example, if there is a record in a table identifying a given status for a user on a table, and it is cited 100 times for 100 different users, you don't want to store all of those redundant values separately.

The second normal form is defined by experts as “eliminating repeating groups,” and “eliminating any partial dependencies among database relations.”

The idea for the second normal form is not quite as straightforward or simple. To comply with the first normal form, you go through the whole table and make sure that none of these have multiple values. That's fairly easy to understand, looking at a diagram where a data table might, for example, have the following identifiers for table contents - name, phone number, state and country, along with a primary key identifying the record number. The first normal form simply has to do with making sure that each data field holds a single value, and not a composite value or multiple values. Here are the basic definitions of each one of these three successive concepts. That's also true for the second normal form as well. However, here's an easy and simple way to think about third normal form, as well as the two normal forms that precede it.Īs you might imagine, much like dimensional complexity, the first normal form is very basic compared to the forms that come after it. These three “normal forms” or normalizations tend to confound people who aren't professional database administrators or mathematicians. Techopedia Explains Third Normal Form (3NF)

Functional dependency 3nf