Voc

Question 1

Why do we need a DB

Answer 1

Avoid redundancy
data integrity
referential integrity
deletion anomalies

Question 2

data integrity

Answer 2

refers to the validity of data

Question 3

avoid redundacy

Answer 3

avoid duplication of information in multiple table within the DB

Question 4

deletion Anomalies

Answer 4

deletion of one of a table results in the deletion of unintended information

Question 5

Referential integrity

Answer 5

ensures that relationships between table remain consistent.

cant add a record to the table that contains the foreign key unless there is a corresponding record in the linked table.

Question 6

redundacy

Answer 6

duplication of information in multiple tables

Question 7

insertion anomoly

Answer 7

user is unable to insert a new record when it should be possible to do so

Question 8

deletion anomoly

Answer 8

record is deleted other information tied to the is also deleted

Question 9

update anomoly

Answer 9

record is updated but other appearances of the same item is not updated.

Question 10

unified modeling language

Answer 10

used to describe conceptual view of the database

Question 11

relational model

Answer 11

formal model of the database

Question 12

relational algebra

Answer 12

a formal language used to symoblically manipulate objects of the relational model

Question 13

tabel model

Answer 13

informal set of terms for relational model objects. terms used to refer to the physical view of the database

Question 14

structured query language

Answer 14

is used to build and manipulate relational databases. based on relational algebra. its is declarative. stadard but some products very on implementatin.

Question 15

uml class or entity

Answer 15

anything in that is to be represented in the db

Question 16

first step of building a db

Answer 16

model it in natural language

Question 17

attribute

Answer 17

is a piece of inofrmation that characterizes each member of a class

Question 18

descriptive atttributes/ natural attributes

Answer 18

those which actually provide real world information about the class. id numbers are not descriptive

Question 19

class diagram

Answer 19

shows the class and its attributes

Question 20

relational scheme

Answer 20

starts with the attributes from the class diagram.

Question 21

sets

Answer 21

domain of all the attributes that belong to a class.

Question 22

Create table nameTable()

Answer 22

creates a table;
CREATE TABLE customers ( 
	cfirstname VARCHAR(20) NOT NULL, clastname VARCHAR(20) NOT NULL, cphone VARCHAR(20) NOT NULL, 
	cstreet VARCHAR(50), 
	czipcode VARCHAR(5));

Question 23

data models

Answer 23

conceptual, logical, physical

Question 24

rows

Answer 24

each instance of the class is represented by a row.

Question 25

tuple

Answer 25

each row is defined in a relational database by a tuple. assigning values to each col.

Question 26

atomicity

Answer 26

prinicple that each tuple only has one piece of data

Question 27

example of assignments in tuples

Answer 27

insert into customer (cfirstname, clastname, cphone, cstreet, czip) values ('tom', 'jewet', '714-555-5555', '100200 slater', '92045');

Question 28

example update

Answer 28

update customers set cphone=714-555-4444' where cphone='714-555-5555';

Question 29

uniqueness

Answer 29

each row is unique no duplicates

Question 30

unordered

Answer 30

we can display them in any order we wantand the meaning does change. we can sort by whatever we want.

Question 31

filter

Answer 31

we can include subsets of rows by specifying criteria

Question 32

superkey

Answer 32

each row must be unique so a set of attributes in each relation scheme mus guarantee uniqueness.

Question 33

primary key

Answer 33

a unique identifier of each row. picked from the super keys

Question 34

example add primary key

Answer 34

``` alter table customers add constraint customer_pk primary key (cfirstname, clastname, cphone); ```

Question 35

example of ensuring uniqueness with one statement.

Answer 35

``` CREATE TABLE customers ( cfirstname VARCHAR(20) NOT NULL, clastname VARCHAR(20) NOT NULL, cphone VARCHAR(20) NOT NULL, cstreet VARCHAR(50), czipcode VARCHAR(5)), CONSTRAINT customers_pk PRIMARY KEY (cfirstname, clastname, cphone); ```

Question 36

association/ relationship

Answer 36

the way that two classes are functionally connected to each other.

Question 37

mulitplicity/cardinality

Answer 37

how few or how many of one class is connected to another class

Question 38

foreign key

Answer 38

the primary key of the parent association | one side is always the parent. and provides the pk attributes to be copied. the many side is the child

Question 39

pk get copied to child as fk mando if

Answer 39

the relationship is mandotory. if its a 1 to * relationship. and information is needed to uniquely identify child

Question 40

identifying

Answer 40

attibutes must be not null

Question 41

referential integrity

Answer 41

ensuring that every fk is connected to the right primary key of the parent.

Question 42

identifying2

Answer 42

if the foreign key is part of the primary key then its identifying

Question 43

non identifying

Answer 43

if fk is not part of the primary key | car example. driver can exist without a car and a car can exist without a driver.

Question 44

candidate key

Answer 44

minimal super key; meaning if you take one attribute away from the set it is no longer unique

Question 45

surrogate Pk

Answer 45

a single small attribute such as a number that has no descriptive value such as an id number

Question 46

substitute pk

Answer 46

a single small attribute such as an abbreviation that has at least some descriptive value

Question 47

3 rules for substitute and surrogate key addition

Answer 47

1. have at least one candidate key 2. is a parent 3. no candidate key small enough for its values to be copied many times into child table. ( to big)

Question 48

external key

Answer 48

already defined by someone else surrogate keys zip codes isbn upc

Question 49

social security

Answer 49

only use as non key feild if required by law

Question 50

discriminator attribute

Answer 50

or partial key) of a weak entity set is the set of attributes that distinguishes among all the entities of a weak entity set on one particular strong entity.

Question 51

normalization

Answer 51

following a procedure or set of rules to insure that a database is well designed. most normalization is to eliminate redundatnt data

Question 52

subkeys always result in redundancy

Answer 52

eliminate it for 3rd normal form

Question 53

signs that you have multiple values attribute

Answer 53

variable length is long plural values have a delimiter, pay attention to order

Question 54

ensureing data integrity

Answer 54

values entered in each field of a table is consistent with its attribute domain.

Question 55

validation rule

Answer 55

constraints on the type of data inserted into col

Question 56

lookup table

Answer 56

tables created for the pupose of storeing enumerated domains

Question 57

enumerated domains

Answer 57

attribute domains that may be specified by a well defined reasonable size set of constant values

Question 58

data definition language (ddl)

Answer 58

used to build and modify the structure of your tables and other objects in the database

Question 59

data manipulation language (dml)

Answer 59

used to work with data in tables

Question 60

data dictionary

Answer 60

contains all information about object in your schema

Question 61

data types

Answer 61

specifies the type of data that an attribute is

Question 62

cross join

Answer 62

in set theory is a cartesian product