Oct 2 In-Class Exercise Thread .
Post your solutions to the Oct 2 In-Class Exercise to this thread.
Best,
Chris
{A}+ = {A} {B}+ = {B} {C}+ = {C} {A, B}+ = {A, B} {A, C}+ = {A, C} {B, C}+ = {B, C} {A, B, C}+ = {A, B, C}
| { |
|---|
| Professor |
| - |
| Pollett |
| - |
| Pollett |
| } |
<br> <br>
| { |
|---|
| Recipe |
| - |
| sauteed scalops |
| - |
| sauteed scalops |
| - |
| Mushrooms a la creme |
| - |
| Mushrooms a la creme |
| } |
R(name, makeModel, year)
(Person1, Toyota Prius, 2012)
(Person1, Nissan Leaf, 2012)
(Person2, Toyota Prius, 2010)
(Person2, Nissan Leaf, 2010)
(Edited: 2019-10-02)Joseph|Nguyen|CS157a Joseph|Nguyen|CS156 Joseph|Tran|CS157a Joseph|Tran|CS156
If we know Joseph we don't know the second column (A --> B)
(Edited: 2019-10-02)Product(Brand, Product Name, Color)
(Adidas, T-shirt, Blue)
(Adidas, Shorts, Blue)
(Adidas, T-shirt, black)
(Adidas, Shorts, black)
(Edited: 2019-10-02)for R(A,B,C) => R(Class Code, Class Title and Year, Class Time)
| { |
|---|
! Class Code !! Class Title and year !! Class Time |-
| 1432 | Computer Networks (2018) | M/W 9-10am | ||
|---|---|---|---|---|
| 1432 | Operating Systems (2019) | M/W 9-10am | ||
| - | ||||
| 1121 | Intro to Database (2018) | F 6-9pm | ||
| - | ||||
| 1121 | Data Structures (2019) | F 6-9pm | ||
| } |
R(A, B, C) (Student1, Class1, Room1) (Student1, Class2, Room2) (Student1, Class1, Room3) (Student1, Class2, Room4)
A multivalue determines B. Yet, A does not fix B.
(Edited: 2019-10-02)This is an example of a multi-valued dependency (MVD) because the name of company (attribute A) fixes a list of possible field (attribute B), including food and cosmestics
A | B |C
Ali | Food | 4.0
Ali | Cosmetics | 2.3
Ali | Food | 3.0
Ali | Cosmetics | 4.3
(Edited: 2019-10-02)R(colA, colB, colC) R(person, house type, purchase date)
(tina, condo, 1928) (paul, townhouse, 2849) (tina, townhouse, 1928) (paul, condo, 2849)
(Edited: 2019-10-02)