PRICE FOR DUPLICATION Three Anomalies Anomaly Anomaly Anomaly Inserts Updates Deletions A new item cannot be added to the database until someone has purchased it: the "purchases" field does not exist unless a purchase has been made. The sword's price is listed in line 300. We change it—and skip one line. Now the database has two entries for the price. We deleted the most recent potion purchase—and the potion itself disappeared along with it. There is no longer any information about this item anywhere. All three stem from the same source: a single fact is recorded in several places. Normalization is a way to eliminate duplicates.