Informal Normalization/Normal Forms

One way of defining Database Normal Forms are using Tuples, Super Keys, Functional Dependency etc. However sometimes those definitions are very abstract and formal and I need some informal definitaion to give me an intuitive way of understanding what these normals are about. Therefore I have put down some informal definition/summary as below.

• 1st Normal Form

  atomic attributes, e.g, no comma delimited list within an attribute/a column

• 2nd Normal Form

  no compound primary key, e.g. if Entity A & B has a many-to-many relationship, joining them via this relationship will result in the normal form being violated

• 3rd Normal Form

  e.g if Entity A & B has a one-to-many relationship, then joining them will result in violation of 3rd normal form.

• BCNF

  e.g. if Entity A & B has a one-to-many relationship and Entity A has a compound key where one key attribute has a one-to-one relationship with B, joining them will result in violation of BCNF.

• 4th Normal Form

  e.g. if many-to-many relationship exists between Entity A & B, and between B & C , the result of joining those relationship will result in violation of 4th Normal Form

• 5th Normal Form

  e.g. if many-to-many relationship exists between Entity A & B, between B & C , and between A & C, the result of joining those relationship will result in violation of 5th Normal Form