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).
For referential integrity to hold in a relational database, any field in a table that is declared a foreign key can contain only values from a parent table's primary key or a candidate key. 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.
Famous quotes containing the word integrity:
“I expect a time when, or rather an integrity by which, a man will get his coat as honestly and as perfectly fitting as a tree its bark. Now our garments are typical of our conformity to the ways of the world, i.e., of the devil, and to some extent react on us and poison us, like that shirt which Hercules put on.”
—Henry David Thoreau (1817–1862)