Introduction
Relations
Relational theory is a prescription for the representation and manipulation of data. It is concerned with the what and not the how. It gives an understanding of DBMSs independent of implementation matters.
There are three components to Relational Theory:
- Structural
- Manipulative
- Constraints
Structural
The constructs from which the data structures of a relational model are built are:
- relations
- attributes
- domains
Manipulative
Manipulation of relations through relational operators aka relational algebra. An alternative method is relational calculus.
Constraints
Constraint definitions form part of a relational model to ensure that only valid combinations of data are contained within a database.
Move on to Structure of Relational Models.
Comments, suggestions, ideas to
Stuart Banner