Normalization – Definitions of Normal Forms

normalization

I've had trouble finding a straight definition of normal forms online.

I don't want any examples or metaphors, just what each form is defined by in a nice format ! I believe there is more than 4 normal forms so it would be greatly appreciated if you could provide the extra information.

Please complete any missing information I've found or lay it out in a better format :

1FN:

  • Each cell is to be single valued
  • Entries in a column must be of the same type
  • Rows must be uniquely identified

2FN:

  • All attributes must be dependent of the key

3FN:

  • Rows must be uniquely identifiable only by the key

4FN:

  • No multi-valued dependencies

Best Answer

You may find this site helpful, too. I think it only goes up to 3NF, however it uses very good examples and clear language:

http://www.essentialsql.com/get-ready-to-learn-sql-database-normalization-explained-in-simple-english/

  • First Normal Form – The information is stored in a relational table and each column contains atomic values, and there are not repeating groups of columns.
  • Second Normal Form – The table is in first normal form and all the columns depend on the table’s primary key.
  • Third Normal Form – the table is in second normal form and all of its columns are not transitively dependent on the primary key