Aug 27 2010
What is Database Integrity
Database Integrity The most general form of integrity constraint is the database constraint. Database constraints reference more than one relation: “A Customer is not allowed to have a status of ‘Preferred’ unless he or she has made a purchase in the last 12 months.” The majority of database constraints take this form. It’s always a [...]
Jul 17 2010
Relational Database Attributes
Relational Database Attributes Your system will need to keep track of certain facts about each entity. These facts are referred to as the entity’s attributes. If your system includes Customer entities, for example, you’ll probably want to know the names and addresses of the customers and perhaps the businesses they’re in. If you’re modeling an [...]