Database Systems (COM1025)
https://labs.azure.com/virtualmachines
1) What is data? Data are raw, unanalysed facts.
▪ Data can be alphanumeric,
images and videos
▪ Data is the building blocks of
information
Data today has volume, velocity, variety – Big
Data
2) What is information? Information is data that has been processed into
a
meaningful form
Information is the base of knowledge and
decision-making.
3) What is knowledge? Knowledge is the capacity to use information for
making decisions.
4) What is a database? A collection of interrelated data, designed for an
organisation’s information needs.
▪ Access to accurate, relevant and
timely information is
critical for most organisations’ success.
5) What are the problems with file based ▪ Storage of duplicate or
databases compared to digital ones? redundant data
▪ Risk of data becoming
inconsistent
▪ Close coupling between
applications and data
▪ Difficult to integrate applications
▪ Difficult to provide concurrent
access to data
6) Why do we use databases? ▪ Data Independence – duplication,
inconsistency
, is minimised
▪ Data Persistence - sharable in a
secure way
▪ Data Abstraction - data models
key to database design
7) How are databases managed?
▪ Database Management System
(DBMS): define, create,
maintain, control access to database
▪ Application Programs: used to
interact with database
8) What is a model? What is a data model? A model is a simplified, miniature or abstract
representation of a real-world object or event
A data model is a collection of concepts for
representing complex real-world data in an
organisation in an abstract way.
▪ Objects/event (entities)
▪ Relationships (e.g. one-to-many,
many-to-many, one-to-one)
▪ Constraints
9) What are the benefits of data modelling? ▪ Provides an abstraction so no
need to be concerned with
, implementation
▪ Facilitates communication
between designer and user by
representing data in an
understandable way
▪ Provides different views to
different users
▪ An accurate data model is key to
good design
10) What is schema? The description of a database at a logical level
(usually in a formal language) supported by the
DBMS’s logical model.
, 11) What are the levels of a schema Physical Level
architecture? ▪ Storage structure of data
External Level
▪ Tailored to be viewed by a
particular category of users
▪ Hides data for security
Conceptual/Internal Level
▪ Defines the logical structure
▪ Bridge between the External
and Physical Levels
12) Why is database design important? ▪ A Database is designed to solve
problems presented by real use
cases
▪ Well-designed database gives
accurate information
▪ Badly designed database can
cause errors that lead to poor
decision making
▪ Data abstraction is key to good
design
▪ A database model consists of
different data models
https://labs.azure.com/virtualmachines
1) What is data? Data are raw, unanalysed facts.
▪ Data can be alphanumeric,
images and videos
▪ Data is the building blocks of
information
Data today has volume, velocity, variety – Big
Data
2) What is information? Information is data that has been processed into
a
meaningful form
Information is the base of knowledge and
decision-making.
3) What is knowledge? Knowledge is the capacity to use information for
making decisions.
4) What is a database? A collection of interrelated data, designed for an
organisation’s information needs.
▪ Access to accurate, relevant and
timely information is
critical for most organisations’ success.
5) What are the problems with file based ▪ Storage of duplicate or
databases compared to digital ones? redundant data
▪ Risk of data becoming
inconsistent
▪ Close coupling between
applications and data
▪ Difficult to integrate applications
▪ Difficult to provide concurrent
access to data
6) Why do we use databases? ▪ Data Independence – duplication,
inconsistency
, is minimised
▪ Data Persistence - sharable in a
secure way
▪ Data Abstraction - data models
key to database design
7) How are databases managed?
▪ Database Management System
(DBMS): define, create,
maintain, control access to database
▪ Application Programs: used to
interact with database
8) What is a model? What is a data model? A model is a simplified, miniature or abstract
representation of a real-world object or event
A data model is a collection of concepts for
representing complex real-world data in an
organisation in an abstract way.
▪ Objects/event (entities)
▪ Relationships (e.g. one-to-many,
many-to-many, one-to-one)
▪ Constraints
9) What are the benefits of data modelling? ▪ Provides an abstraction so no
need to be concerned with
, implementation
▪ Facilitates communication
between designer and user by
representing data in an
understandable way
▪ Provides different views to
different users
▪ An accurate data model is key to
good design
10) What is schema? The description of a database at a logical level
(usually in a formal language) supported by the
DBMS’s logical model.
, 11) What are the levels of a schema Physical Level
architecture? ▪ Storage structure of data
External Level
▪ Tailored to be viewed by a
particular category of users
▪ Hides data for security
Conceptual/Internal Level
▪ Defines the logical structure
▪ Bridge between the External
and Physical Levels
12) Why is database design important? ▪ A Database is designed to solve
problems presented by real use
cases
▪ Well-designed database gives
accurate information
▪ Badly designed database can
cause errors that lead to poor
decision making
▪ Data abstraction is key to good
design
▪ A database model consists of
different data models
