How to group data , Sub-queries & questions: Enhancing(SQL) (Part-4)

PRE-REQUISTES PART-1 (Understand concept of all keys (theory) and what are anomalies in database) PART-2 (CRUD operations in database , learn syntax & understand concept by doing) PART-3 (1st Normal form , 2NF , 3NF , Partial Dependency , Transitive ...