Constraint Rules


Constraints are rules that prevent things from happening. The most common constraint is to prevent an update to the database. For example, a foreign key constraint will stop an update to a database if the foreign key is not resolved. (If there is a foreign key constraint that says all order line items must have an item number that matches a primary key in the inventory master table, any attempted updates to the order line table with missing or nonmatching item numbers will fail to update.)

In the relational database world these constraints are coded as declarative statements. In contrast, in business rules the constraints are subtyped into various types and then each one is instantiated with its appropriate parameters.

Each business rule practitioner and product vendor has its own taxonomy of rules. Some of the more common include the following:

  • Cardinality constraints, also called instance verifiers, ensure that there are the proper number of related items or properties.

  • Type verifiers ensure that related items conform to type.

  • Range and value constraints ensure that a property is within a numeric range.

  • Logical connectors, such as mutually exclusive or inclusive, restrict an item to be either one of a set of possible values or any number of a set of possible values.




Semantics in Business Systems(c) The Savvy Manager's Guide
Semantics in Business Systems: The Savvy Managers Guide (The Savvy Managers Guides)
ISBN: 1558609172
EAN: 2147483647
Year: 2005
Pages: 184
Authors: Dave McComb

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