3.1.15 Database Concepts

Question 1

what database satisfies these requirements:

data is gathered, collated and analysed?

Answer 1

relational database

Question 2

what is a table?

Answer 2

a two-dimensional representation of data (stored in rows and columns)

Question 3

how many tables does a flat file database have?

Answer 3

only 1 table

Question 4

how many tables does a relational database have?

Answer 4

several tables linked together

Question 5

what is a relational database?

Answer 5

a database structured to recognise relations between stored items of information.

Question 6

why does each table need a new name?

relational database

Answer 6

so that the database management systems can be found in the right table

Question 7

What is the standard user interface to any relational database?

Answer 7

structured query language (SQL)

Question 8

why is SQL used?

Answer 8

for the purpose of:
- retrieving information from a relational database
and
- for gathering data for reports

Question 9

what is the benefit of a relational database over a flat file database?

Answer 9

it’s straightforward to extend

Question 10

what does RDBMS stand for?

Answer 10

Relational DataBase Management System

Question 11

what are the 3 basic components of RDBMS?

Answer 11

• a store
• a method of creating and retrieving data
• a method of ensuring that data is logically consistent

Question 12

what is a table also referred to in a relational database?

Answer 12

‘relation’

Question 13

what does a relation store and in what structure?

Answer 13

a two-dimensional structure use to store RELATED information

Question 14

what does a relational database consist of?

Answer 14

2 or more related tables

Question 15

what is a record? {3}

Answer 15

• a complete single set of information
• comprised of fields
• a set of records creates a file

Question 16

what is a row within a relation?

Answer 16

one record

Question 17

what does a column within a database table contain?

Answer 17

all the information of a single type

Question 18

what types of data are columns formatted to accept?

Answer 18

(such as:)

• integers
• Booleans
• decimals (real)
• strings

Question 19

what is a field?

Answer 19

a single piece of data that can be retrieved from a database
(like a cell in a spreadsheet)

Question 20

what piece of information is a field in an SQL and what does it form part of?

Answer 20

it is the smallest piece of information

forms part of an individual record

Question 21

what is a database query?

Answer 21

a question you put to the database

Question 22

what is the outcome of a query?

Answer 22

the information that’s returned by the database to answer the question

Question 23

how are queries created

Answer 23

using SQL which looks like high-level programming language

Question 24

every table in a relational database should contain how many primary keys?

Answer 24

1 or more columns that are assigned as the primary key

Question 25

what is the crucial fact for the primary key to work?

Answer 25

the value it holds must be unique for each of the records within the table

Question 26

how do data relationships work?

Answer 26

by comparing data in key fields between fields that have corresponding names in linked tables
(basically: by comparing the primary key with the foreign key)

Question 27

the fields contain the _______ ___ for one of the _____, which then supplies…

Answer 27

the fields contain the PRIMARY KEY for one of the TABLES, which then supplies THE UNIQUE IDENTIFIER FOR EACH RECORD AND THE ‘FOREIGN’ KEY IN THE OTHER TABLE

Question 28

what is the foreign key?

Answer 28

a collection of attributes intended to match the primary key of a different table

Question 29

how is a link established between 2 tables?

foreign key

Answer 29

by adding the column that holds the primary key in the 1st table to the 2nd table (becomes foreign key in 2nd table)

Question 30

3.1.15.1 Query methods (SQL)

Answer 30

press 5 to move on

Question 31

what are all SQL codes written in the form of?

Answer 31

a query statement and this is ‘executed’ against a database

Question 32

SQL queries perform…

Answer 32

a data operation (e.g selecting, inserting/updating, or creating data objects)

Question 33

what does every query statement begin with? {4}

Answer 33

• DELETE
• CREATE
• SELECT
• UPDATE

Question 34

SQL databases can be created on…

Answer 34

a single machine

Question 35

often large databases…

Answer 35

are shared between users

Question 36

how are large databases shared?

Answer 36

by installing them on a dedicated server

Question 37

3.1.15.2 Connecting to databases from applications and web-based apps

Answer 37

press 5 to move on

Question 38

2 web-based programming languages

Answer 38

SQL and PHP

Question 39

other web-based languages:

Answer 39

ASP,
ASP.NET,
Perl and JSP

Question 40

by storing data in web-based applications, what have new technologies led to?

Answer 40

‘distributed applications’

Question 41

distributed applications…

Answer 41

have many parts that are stored on virtual machines

Question 42

do the virtual machines have to be on the same systems?

Answer 42

no they can be on the same or different systems

Question 43

(virtual machines can be on different systems) what does this allow?

Answer 43

allows smartphones to access the same resources as desktop computers

Question 44

what are the 2 kinds of distributed software?

Answer 44

• web-based

- client-server

Question 45

what is web-based software?

Answer 45

allows companies to only pay for what they need and to grow into the system without large upfront costs

(usually paid for on a subscription/ usage basis)

Question 46

what is client-server software?

Answer 46

usually paid for upfront and the initial cost of the system can be high

Question 47

advantages of client-server networks over web-based applications: {3}

Answer 47

• you are in control of upgrades and don’t have to update to the latest versions if you don’t want to
• you have to manage your systems and pay for the technical support
• applications tend to run faster when they’re local to the user’s computer

Question 48

check your understanding question:

what is a database? {2 marks}

Answer 48

databases use a series of tables to store data. a table is a 2-dimensional representation of data stored in rows and columns

Question 49

check your understanding question:

how does a relational database differ from a flat file database?

Answer 49

a flat file database has 1 table, similar to a spreadsheet. a relational database has multiple linked tables