Friday, March 7, 2008

Strictly, a relational database is a collection of relations (frequently called tables). Other items are frequently considered part of the database, as they help to organize and structure the data, in addition to forcing the database to conform to a set of requirements.

Relations or tables

Main article: Constraint Constraints

Main article: data domain Data domain

Main article: Superkey Keys

Main article: Foreign key Foreign keys

Main article: Transition constraintRelational database Transition constraints
Other constraints of various different kinds can be created to enforce various kinds of business rules. They can be as simple as "the number of cars an individual owns must be non-negative" or complex patterns like "If the work that an employee performs is 'Hazardous Materials Transport' then that employee's age must be at least 18 years, and the employee's certifications must include 'Hazmat endorsement', and company insurance for that employee must include life insurance."

Other constraints

Main articles: Relvar and View (database) Relvars

Main article: Stored procedure Stored procedures

Main article: Index (database) Relational operations

Main article: Database normalization

No comments: