BE - Database Management Systems

Insertion anomaly happens when it's hard to add new data because other unnecessary data is required.

Deletion anomaly happens when removing one piece of data causes important related data to be lost. Both issues occur in poorly designed tables and are fixed by normalization.

Insertion Anomaly: Suppose a company’s table mixes employee and department info in one place. If a new department is created and doesn’t have any employees yet, the table design might stop you from entering that department’s details until someone is hired.

Deletion Anomaly: If there’s just one employee in a department and that person leaves, deleting the employee from the table might also delete information about the whole department—losing details that should be kept.