session 7: fundamentals of relational database operations

Question 1

data file

Answer 1

collection of logically related records

Question 2

data hierarchy

Answer 2

bit
byte
field
record
data file/table
database

Question 3

bit def

Answer 3

smallest unit of data, 0 to 1

Question 4

byte def

Answer 4

group of 8 byte, single character

Question 5

field def

Answer 5

logical grouping of characters into a word, a small group of words, identification #

Question 6

record def

Answer 6

logical grouping of related fields such as student’s name, the course taken and the grade

Question 7

data file/table

Answer 7

logical grouping of records

Question 8

relational database

Answer 8

collection of interrelated two-dimensional tables consisting of rows and columns

Question 9

DBMS data base management system

Answer 9

set of programs with tools to create and manage databases. Meaning adding, deleting, accessing, modifying, and analyzing data that are stored in the database.
Can access the data with query and reporting tools or apps.

Question 10

DBMS minimizes

Answer 10

data redundancy
data isolation: application cannot access data associated with other apps
data inconsistency

Question 11

DMBS maximizes

Answer 11

Data security: data is put in one place, risk of losing it all at once
Data integrity: meets certain constraints
Dara independence: applications and data independent so all apps are able to access same data

Question 12

data model def

Answer 12

a diagram that represents entities in the database and their relationships

Question 13

entity def

Answer 13

a person, place, thing about whihc an organization maintain info about

Question 14

instance def

Answer 14

each row in a relational table which is a specific unique representation of the entity
ex: entity is student and instance of the entity would be a particular student

Question 15

attribute def

Answer 15

each characteristic or quality particular to an entity
ex: if entity is customers attribute would be name , employee number and product colour

Question 16

primary key def

Answer 16

the identifier field or attribute

Question 17

foreign key def

Answer 17

a field or group of field in 1 unique table that uniquely identifies a row of another table

Question 18

secondary key def

Answer 18

a field that has some identifying info but typically does not identify the record with complete accuracy

Question 19

query language

Answer 19

Structured Query Language (SQL)
Query by Exqmple (QBE)

Question 20

SQL

Answer 20

allows people to do complicated searches by using relatively simple statements/key words (SELECT, FROM, WHERE)

Question 21

QBE

Answer 21

the users fill out a grid or template (“form”) to construct a sample or description of data desired

Question 22

relationships illustrate…

Answer 22

….an association between entities

Question 23

degree of relationships

Answer 23

number of entities associated with a relationship

Question 24

entity-relationship diagram (ERD)

Answer 24

doc that shows data entities + attributes + relationships among them

Question 25

business rules def

Answer 25

precision description of policies/procedures/principles in any organization

Question 26

data dictionary def

Answer 26

provides info on each attribute such as its name

Question 27

relationships type

Answer 27

unary binary ternary

Question 28

unary relationship def

Answer 28

a relationship that exists when an association is maintained within a single entity

Question 29

binary relationship def

Answer 29

a relationships that exists when 2 entities are associated

Question 30

ternary relationship def

Answer 30

a relationship that exists when 3 entities are associated

Question 31

cardinality def

Answer 31

max number of times an instance of an entity can be associated with an instance in the related entity

Question 32

connectivity def

Answer 32

describes the relationship classification

Question 33

normalization def

Answer 33

method for analyzing/reducing a relational database to its most streamlined form limit redundancy, maximum integrity and optimal processing performance 1st normal form to 3rd

Question 34

functiunal dependencies def

Answer 34

a means of expressing that the value of one particular attrbute is associated with or determines a specific single value of another attribute

Question 35

join operation def

Answer 35

a database operation that combines records from 2 or more tables in a database

Question 36

relational database model def

Answer 36

usually designed with a number of related tables each of which contains records (listed in rows) and attributes (listed in columns)

Question 37

advantage and disadvantages of relational databases

Answer 37

enable people to compare info quickly by row or column users can easily retrieve items by finding the point of intersection of a particular row and column large scale relational database can be composed of numerous interrelated tables => design more complex => slow search and access time

Question 38

entity relationship modelling def

Answer 38

the process of designing a database by organizing data entities to be used and identifying the relationships among them

Question 39

third normal form characteristics

Answer 39

free of data redudancy all foreign keys appear where needed to link related tables