What type of shop does the widow have ?
The table structure generated by Bernstein 's schema generation algorithm is actually EKNF , although that enhancement to 3NF had not been recognized at the time the algorithm was designedIf a referential integrity constraint is defined to the effect that { Shop Type , Nearest Shop } from the first table must refer to a { Shop Type , Shop } from the second table , then the data anomalies described previously are prevented .