Relational Integrity
See: Relational DDBMS, Relation, Relational Table.
References
2013
- http://en.wikipedia.org/wiki/Referential_integrity
- Referential integrity is a property of data which, when satisfied, requires every value of one attribute (column) of a relation (table) to exist as a value of another attribute in a different (or the same) relation (table).[1]
For referential integrity to hold in a relational database, any field in a table that is declared a foreign key can contain either a null value, or only values from a parent table's primary key or a candidate key.[2] In other words, when a foreign key value is used it must reference a valid, existing primary key in the parent table. For instance, deleting a record that contains a value referred to by a foreign key in another table would break referential integrity. Some relational database management systems (RDBMS) can enforce referential integrity, normally either by deleting the foreign key rows as well to maintain integrity, or by returning an error and not performing the delete. Which method is used may be determined by a referential integrity constraint defined in a data dictionary.
- Referential integrity is a property of data which, when satisfied, requires every value of one attribute (column) of a relation (table) to exist as a value of another attribute in a different (or the same) relation (table).[1]
- ↑ Mike Chapple. "Referential Integrity". http://databases.about.com/: About.com. http://databases.about.com/cs/administration/g/refintegrity.htm. Retrieved 2011-03-17. "Definition: Referential integrity is a database concept that ensures that relationships between tables remain consistent. When one table has a foreign key to another table, the concept of referential integrity states that you may not add a record to the table that contains the foreign key unless there is a corresponding record in the linked table."
- ↑ Coronel et al. (2013). Database Systems 10th ed. Cengage Learning, ISBN 978-1-111-96960-8