Flashcards in Function Dependencies & Normalization Deck (19):

1

## Types of update anomalies

### Insertion, Deletion, Modification

2

## Functional Dependencies

###
Given X->Y, the attributes X will determine the attributes Y uniquely.

Y is functionally dependent on X

X functionally determines Y

3

## Full functional dependencies

### Given X->Y, there can be no attributes taken out of X such that X can still determine Y

4

## 1NF

###
All domain values in R are atomic.

In other words, no nested values, lists of attributes etc.

5

## 2NF

###
R is in 1NF AND every non-key attribute if fully dependent on the primary key.

In other words, each non-candidate key needs to be only identified by the entire primary key, not just part of it.

6

## 3NF

###
R is in 2NF AND every non-key attribute is non-transitively dependent on the primary key.

In other words, there are not any attributes that depend on the status of other non-prime attributes

7

## BCNF

###
Boyce-Codd Normal Form:

Every functional dependency of the relation, R, is determined by primary key(s) only.

8

## Superkey

### Attributes that uniquely identity a tuple

9

## Key

### A minimal superkey

10

## Candidate Key

### A key that could uniquely identity a relation

11

## Alternate key

### A secondary key that could have been the primary key

12

## Foreign key

### A key that maps to another entity

13

## Natural Key

### Keys that exist in the real world, ssn,

14

## Composite key

### Keys with two or more attributes

15

## Surrogate Key

### Key with no real world meaning, opposite of a natural key

16

## Surrogate Key VS Natural Key

### When choosing a Primary Key it is best to use a natural key.

17

## Non-loss decomposition

### When a relation is decomposed, can it be composed again without loss of any data.

18

## 4NF

### When a relation has multi-valued dependancies

19