Violating referential integrity

When REFERENTIAL INTEGRITY is enforced between two fields in related tables, each time the record containing either field is edited, the additions or changes must conform to the type of relationship set between those fields in the two related tables. When a record is to be saved, if any of its fields violates referential integrity, the record will not be saved, and this error message will be displayed.

Referential integrity can be violated by the following actions, as well as by other mistakes or incorrect entries: 1) a user enters a data type different from that field's designed data type, either in that table or a related table, 2) a user tries to change the data type of a related table when updating the database design, 3) a user's entry does not fit in the designed field length of that table or a related table.