Back to the Basics - Second Normal Form

This is the second article on normalized data structures. Click here to read about First Normal Form.

Second Normal Form

Second Normal Form (2NF) can only exist if a dataset complies with 1NF and each record has a unique compound key. A compound key uses more than one field to uniquely identify a record.

The dataset above requires two fields to unique identify each row: Year and Winner. Therefore this table is compliant with 2NF.

If a table does not have a compound key, then 2NF is automatically equivalent to 1NF.

Because 1NF and 2NF do not provide much value in a querying environment, they are rarely discussed in the real world. Either a table is 3NF compliant or it is not normalized at all.

However, the prevalence of spreadsheets means many datasets are created with a completely free data structure. Data can be organized in a spreadsheet without regard to any database rules, and as long as the data stays in a spreadsheet this isn't a problem. The challenges comes when spreadsheet data needs to be loaded into a database system or data warehouse -- that's when the need for structured data becomes apparent.