Most databases provide adequate data integrity when  'normalized' to third normal form.

First Normal Form

  1. Eliminate repeating groups in individual tables.
  2. Create a separate table for each set of related data.
  3. Identify each set of related data with a primary key.  

Second Normal Form

  1. Create separate tables for sets of values that apply to multiple records.
  2. Relate these tables with a foreign key.  

Third Normal Form

  1. Eliminate fields that do not depend on the key.  

Fourth Normal Form

  1. In a many-to-many relationship, independent entities can not be stored in the same table.  

Fifth Normal Form

  1. The original table must be reconstructed from the tables into which it has been broken down.