Database normalisation

The method for designing a relational database is to use a process commonly known as normalisation. The goal of database normalisation is to:

• Decide if a given relation schema is in ‘good form’.
• If a given relation schema is not in ‘good form’, losslessly decompose it into a number of smaller relation schemas, each of which is in an appropriate good form.

Database normalisation theory is based on functional dependencies and multivalued dependencies.

Notational conventions

• Greek letters $(\alpha ,\beta ,\cdots )$ are used for attributes.
• $K$ denotes a set of attributes which is a superkey.
• Lowercase names $(r,s,\cdots )$ are used for relations. Uppercase names $(R,S,\cdots )$ are used for relation schemas.
  • $r(R)$ denotes the relation $r$ with schema $R$.