Joe Celko s SQL for Smarties - Advanced SQL Programming P12. In the SQL database community, Joe Celko is a well-known columnist and purveyor of valuable insights. In Joe Celko's SQL for Smarties: Advanced SQL Programming, he picks up where basic SQL training and experience leaves many database professionals and offers tips, techniques, and explanations that help readers extend their capabilities to top-tier SQL programming. Although Celko denies that the book is about database theory, he nevertheless alludes to theory often to buttress his practical points. This title is not for novices, as the author points out. Instead, its intended audience. | 82 CHAPTER 2 NORMALIZATION Given 1 day hour gate - pilot 2 day hour pilot - flight prove that day hour gate - flight. 3 day hour - day hour Reflexive 4 day hour gate - day hour Augmentation on 3 5 day hour gate - day hour pilot Union 1 4 6 day hour gate - flight Transitive 2 and 5 . The answer is to start by attempting to derive each of the FDs from the rest of the set. What we get is several short proofs each requiring different given FDs in order to get to the derived FD. Here is a list of each of the proofs used to derive the ten fragmented FDs in the problem. With each derivation we include every derivation step and the legal FD calculus operation that allows us to make that step. An additional operation that we include here which was not included in the axioms we listed earlier is left reduction. Left reduction says that if XX Y then X Y. The reason it was not included is that this is actually a theorem and not one of the basic axioms a side problem can you derive left reduction . Prove day hour pilot - gate a day - day Reflexive b day hour pilot - day Augmentation a c day hour pilot - day flight Union 6 b d day hour pilot - gate Transitive c 3 . Prove day hour gate - pilot a day - day Reflexive b day hour gate - day Augmentation a c day hour gate - day flight Union 9 b d day hour gate - pilot Transitive c 4 . Prove day flight - gate a day flight pilot - gate Pseudotransitivity 2 5 O Domain-Key Normal Form DKNF 83 b day flight day flight - gate Pseudotransitivity a 4 c day flight - gate Left reduction b . Prove day flight - pilot a day flight gate - pilot Pseudotransitivity 2 8 b day flight day flight - pilot Pseudotransitivity a 3 c day flight - pilot Left reduction b . Prove day hour gate - flight a day hour - day hour Reflexivity b day hour gate - day hour Augmentation a c day hour gate - day hour pilot Union b 8 d day hour gate - flight Transitivity c 6 . Prove day hour pilot - flight a day hour - day hour Reflexivity b .
