introduction

Question 1

what is data

Answer 1

anything that can be represented in binary

Question 2

what is data engineering

Answer 2

designing and building systems so data can ve collected managed and analysed

Question 3

what is a database

Answer 3

structured systems for storing retrieving and managing data

Question 4

what is raw data

Answer 4

data kept in an excel file

Question 5

data model

Answer 5

defines how data will be related and stored

Question 6

what are some negatives of file processing applications

Answer 6

would have to hire a developer as they were hard to implement which is expensive
issues with optimisation performance reliability and reuse

Question 7

what is a file processing application

Answer 7

a set of files that are processed to retrieve information

Question 8

logical model

Answer 8

allows a logical representation which aids processing which can be represented graphically via an entity relationship diagram

Question 9

dbms

Answer 9

database management system; uses the logical model to control the database and provides efficient reliable multi-user storage and access to large amounts of persistent data

Question 10

what is the difference between source code, a program, and software

Answer 10

source code; code written by developers that isn’t directly executable
program; what you get when the source code is executed
software; the entire collection of programs, libraries and related data

Question 11

ddl (data definition language)

Answer 11

creates tables

Question 12

dml (data manipulation language)

Answer 12

modifies tables

Question 13

what is an entity and how is it represented in an er diagram

Answer 13

an object with distinguishable attributes
rectangle

Question 14

entity set

Answer 14

a representation of entities with the same set of attributes

Question 15

what is an attribute and how is it represented in an er diagram

Answer 15

information that describes an aspect of an entity
oval

Question 16

primary key

Answer 16

unique identifier for an entitiy

Question 17

what is a derived attribute and how is it represented in an er diagram

Answer 17

an imaginary attribute not stored in the database but derived using system recourses
dashed/broken oval

Question 18

what are multi-valued attributes and how are they represented in an er model

Answer 18

attributes with more than one value
double oval

Question 19

composite attributes

Answer 19

an imaginary group of attributes not in the table that groups together existing attributes

Question 20

relation

Answer 20

a logical model for associating 2 or more entities

Question 21

what is a relationship set and how is it represented in an er model

Answer 21

a set of all relationship that can have attributes and a primary key
diamond

Question 22

degree of relationship set

Answer 22

number of different entity sets in the relationship

Question 23

one to one relationship

Answer 23

created whilst creating the table and can lead to new tables

Question 24

total participation (must)

Answer 24

for every entity in an entity set, it must relate to at least another entity in the other set

Question 25

partial participation (may)

Answer 25

not all entities have to map to another entity in the other set

Question 26

what is combined to create the subject table key

Answer 26

owner table primary key + subject table weak key

Question 27

overlap constraints

Answer 27

restrictions on the relationship between different entities, ensuring that they don't simultaneously occupy conflicting roles

Question 28

covering constraints

Answer 28

ensures that everything is correctly classified within the appropriate categories and leaving no gaps in the er model

Question 29

what are the 2 reasons that we use ISA

Answer 29

identifies entities that participate in relationships adds descriptive attributes to a specific subclass