Chapter 6 Normalization

More documents

Recommendations

Info

A bit review The essential requirement imposed by an FD is an implication, A → B. Conceptually, implication comes with the following truth table. A B A → B F F T F T T T F F T T T Thus, the only case an implication fails is when A holds, while B does not. In other words, if A holds, then to ensure the implication constraint holds, B must hold. For example, when I say “If I have $5, the lunch is on me.” the only case you can say I lie is when I do have $5, but don’t buy you lunch. 12
FD examples Given the following value of a table SCP, telling us some suppliers with a home base supply a certain number of parts. S# CITY P# QTY S1 London P1 100 S1 London P2 100 S2 Paris P1 200 S2 Paris P2 200 S3 Paris P2 300 S4 London P2 400 S4 London P4 400 S4 London P5 400 13
Page 1 and 2: Chapter 6 Normalization Conceptual
Page 3 and 4: Remember this one Consider the foll
Page 5 and 6: Another abnormally Assume that we w
Page 7 and 8: Decomposition The solution to the a
Page 9 and 10: What have we learned 1. Decompositi
Page 11: Technically, ... ..., a functional
Page 15 and 16: What do we really want We notice th
Page 17 and 18: Key is a special FD Note that the k
Page 19 and 20: Identify the FDs... Consider the ta
Page 21 and 22: The bad guy Consider the following
Page 23 and 24: What is happening As a result, we h
Page 25 and 26: What does that mean Every RDB is in
Page 27 and 28: The BCNF A relation schema S = (R,
Page 29 and 30: BCNF states that if this is the cas
Page 31 and 32: 4. A relation instance that is in a
Page 33 and 34: 5. BCNF relations with more than on
Page 35 and 36: 3NF could be redundant We saw earli
Page 37 and 38: A plan Since there is no redundancy
Page 39 and 40: An example Consider the following s
Page 41 and 42: An example The decomposition of Has
Page 43 and 44: A bit too late ..., which we will o
Page 45 and 46: BCNF Decomposition Let S 0 = (R, F)
Page 47 and 48: Via 3NF If we settle for 3NF, it is

Chapter 6 Normalization

Create successful ePaper yourself

Delete template?

Save as template?