ch4

Question 1

relation

Answer 1

named 2D table of data. consists of the named columns(attributes)

Question 2

primary key

Answer 2

unique ID for a row. underline it. AKA identifier

Question 3

composite key

Answer 3

primary key that is composite

Question 4

foreign key

Answer 4

primary key of one table stored in another table to establish relationship. dashed underline.

Question 5

schema

Answer 5

overall logical structure of the database

Question 6

difference between table and relation

Answer 6

relations pretty much cannot have repeats

Question 7

integrity constraints

Answer 7

rules to make sure data is accurate and good

Question 8

domain

Answer 8

set of values that may be assigned to attribute

Question 9

entity integrity rule

Answer 9

make sure primary key is valid and unique, not null

Question 10

null

Answer 10

absence of a value

Question 11

referential integrity constraint

Answer 11

check if foreign keys are good

Question 12

well-structured relation

Answer 12

minimal redundancy, allows modification and deletion with minimal headaches

Question 13

anomaly

Answer 13

inconstancy that happens when you try to update a table with redundant data. three types: insertion, deletion, and modification anomalies

Question 14

transforming EER into relations steps

Answer 14

1-map regular entities
2-map weak entities
3-map binary relationships
4-map associative entities
5-map unary relationships
6-map ternary (and n-ary) relationships
7-map supetype/subtype relationships

Question 15

descriptors

Answer 15

non key attributes

Question 16

surrogate primary key

Answer 16

different way of identifying weak entity, just generate a unique serial number. good way to simplify key structure.

Question 17

identifying relationship

Answer 17

in weak entities, owner relation

Question 18

partial identifier

Answer 18

unique part of weak entity. NOT primary key, primary key will be composite of owner and the partial id

Question 19

natural key

Answer 19

as oppossed to surrogate key, has meaning to organization P170

Question 20

recursive foreign key

Answer 20

foreign key in a relation references primary key of same relations. unary primary/foreign

Question 21

normalization

Answer 21

decompose relations with anomalies to produce smaller more well structured ones

Question 22

normalization main goal

Answer 22

decide which attributes should be grouped together to AVOID ANOMALIES

Question 23

normal form

Answer 23

attributes have to follow rules between them to be valid

Question 24

functional dependency

Answer 24

constraint between two attributes in which one attribute is determined by another. like a function, follows a one to one mapping.

Question 25

determinant

Answer 25

attribute on the left side of arrow in a functional dependency

Question 26

candidate key

Answer 26

attribute or group of attributes that can uniquely identify row