An unnormalised table records (student, course, course_fee). When the last student enrolled in a course withdraws and the row is deleted, the course fee is lost too. Which anomaly is this?
Correct answer A. Deletion anomaly
Explanation
A deletion anomaly happens when removing one fact, here an enrolment, unintentionally removes another independent fact, the course fee, because both live in the same row. An insertion anomaly is the reverse: you cannot record a new course's fee until a student enrols. An update anomaly arises when a repeated value must be changed in many rows. A dirty read is a concurrency problem, not a design problem.
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