Page "Database normalization" Paragraph 14

* Under certain circumstances, deletion of data representing certain facts necessitates deletion of data representing completely different facts.

The " Faculty and Their Courses " table described in the previous example suffers from this type of anomaly, for if a faculty member temporarily ceases to be assigned to any courses, we must delete the last of the records on which that faculty member appears, effectively also deleting the faculty member.

This phenomenon is known as a deletion anomaly.