Download Databases

Databases
Session - Overview
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What is our starting point? Introductions!
Databases
Database Management System
Relational Databases
Query Methods
Problem areas for student learning.
Databases – Definition
• “A database is a persistent organised store of
data”
• Persistent? – Data is retained even when the
application is not in use.
• Organised? – The data is logically structured to
enable easy storage, retrieval and
manipulation of information.
• Store of data? – Granular level information,
grouped together to describe an entity
Databases - Definition
• A database does not have to be electronic.
• An address book, that most people have, is a
database. The book itself provides a structure
to contain the information.
• So formally the term database describes both
the data and supporting data structures.
Database Management Systems (DBMS)
• A database
management system is
a software package that
manages access to a
database.
• Microsoft Access,
Oracle, SQL Server,
MySQL, and many new
freebies on the Cloud!
DB
DBMS
Database Management Systems (DBMS)
• A database
management system is
a software package that
manages access to a
database.
• Microsoft Access,
Oracle, SQL Server,
MySQL, and many new
freebies on the Cloud!
Database System
DB
DBMS
Database Management Systems (DBMS)
Application
SQL
www
DBMS
DB
Database Management Systems (DBMS)
• Your database is simply a
holding place for your
data. It isn’t capable of
doing anything other than
that.
• The DBMS is what allows
us to interact with the
database. It allows us to
design, build and
maintain the database
and once built we can.....
• Create
• Read
• Update
• Delete
Relational Databases: Entities
• An entity is anything which can be uniquely
described by a set of attributes
(characteristics/properties)
– E.g. A gallery, a painting, an artist, a supplier, an
exhibition.
– A gallery can be uniquely described by its name,
address, postcode, telephone number etc. Therefore a
gallery is an entity.
– Think of attributes that may uniquely describe the
other entities.
• An entity is a concept
Relational Databases: Tables
• A table is the physical form of an entity.
• A field is the physical form of an attribute
• E.g. A gallery is an entity which will have its own table where
the details of particular galleries may be stored.
Fields
Name
Address
PostCode
Telephone
Mima
Middlesbrough
TS1 3BA
01642 123456
Tate Modern
London
L13 3RF
0845 123456
Baltic
Gateshead
NE14 1TH
0845 654321
Records
• The collection of data for each name constitutes a record
• Within each record the information is held in fields
Organisation
Poor Example – too much repetition
Artist Name
Andy Warhol
Andy Warhol
Andy Warhol
Artist DOB Artist Origin
06/08/1928 USA
07/08/1928 USA
08/08/1928 USA
Painting Title
Marilyn
Eight Elvises
Campbell's soup
Genre
Pop Art
Pop Art
Pop Art
Date
1961
1963
1962
Organisation
Better Example – but how are they linked?
Artist Name
Andy Warhol
Artist DOB
06/08/1928
Artist Origin
USA
Painting Title
Marilyn
Eight Elvises
Campbell's soup
Genre
Pop Art
Pop Art
Pop Art
Date
1961
1963
1962
Organisation
Perfect Example – both tables linked using KEYS!
Primary key
Artist ID
Artist Name
Artist DOB
Artist Origin
1
Andy Warhol
06/08/1928 USA
Painting Title
Genre
Date
Artist ID
Marilyn
Pop Art
1961
1
Eight Elvises
Pop Art
1963
1
Campbell's soup Pop Art
1962
1
Foreign Key
Relationships between tables
A gallery can display many paintings
• A relational database allows
tables with common
information to be
connected.
• E.g An gallery displays
paintings, and artists create
paintings.
• Rather than putting all the
information into one table
we can split it into 3 to
avoid repetition of records
• This organisation causes
confusion amongst
students!
Gallery
0..n
THE
DATA
MODEL
Painting
1..n
Artist
An artist can create many paintings
Major Components of Database System
• Tables
• The table structures will hold data on areas that are
needed, eg galleries, artists and paintings.
• Queries
• There would be no point having tables of stored data if they
cannot access it. A DBMS allows you to set up queries to
pull out information, e.g. all artists born before 1850.
Queries allow you to select, insert, update and delete data.
• Reports
• To give formalised output of information and can include
data from more than one table, e.g. All artists exhibiting at
Mima in January. Can also include summaries/processed
calculations.
TIME FOR SOME EXAMPLES
Resources
• This is a large subject, with some of the topics only touched upon
here, but a full set of workbooks will accompany this workshop
• Useful references...
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Sample data models
Microsoft Dynamic Data
Zoho Creator
Mendix
Caspio
Microsoft Lightswitch
• Any questions?
• During the break please think about which areas you would
like to explore further.....
Take a break!