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Chapter 22. Exploring Relational Databas... > Enforcing Database Integrity

Enforcing Database Integrity

The integrity of a database is comprised of two elements: entity and referential integrity. Entity integrity requires that all primary keys must be unique within a table, and referential integrity dictates that all foreign keys must have corresponding values within a base table's primary key. Although the normalization process creates entity and referential integrity, either the RDBMS itself or your application must maintain that integrity during the data-entry process. Failure to maintain database integrity can result in erroneous data values and, ultimately, widespread corruption of the entire database.

Ensuring Entity Integrity and Auditability

Database managers differ widely in their capabilities to maintain entity integrity through unique primary key values. Paradox, for instance, enforces unique primary keys within the RDBMS by flagging as a key violation any attempt to insert a row with an identical primary key. Paradox then places the offending record in the KeyViol table. Access uses a similar technique when you specify a no-duplicates index. If you paste or append records that have duplicate primary keys, Access appends those records to a Paste Errors or Append Errors table.


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