Database: is a collection of data or information
which is held together in an organised or
logical way. (Paper based or computerised)
Paper Based
i.e notebook with addresses sorted by
surname or the Yellow Pages directory
which is organised by businesses.
Computerised
i.e. search engines (Google),
school electronic registers
Why use a database?
Vast amounts of information can
be stored
Banks: millions of customers, who might have more than one account
(current, savings, mortgage). Many transactions will take place so the
bank will need to store details of every single transaction that takes
place, what time, how much, who was paid etc.
Queries can be run to search for
specific records or groups of records
Bank: A customer may complain about a withdrawal of
money that they do not recognise. Bank will need to search
its database very quickly and find the customers account,
transaction and details - can be done in seconds.
Reports can be produced from the
data stored or queries run
Data can be sorted into a logical order or extracted as
part of a query, but the output doesn't look very
professional. If you are showing the information to a
customer, producing a database report may be required.
Information can be extracted from the
database and exported into a word
processing package for mail merging
Spam can be sent be running queries on a database and
then finding a set of records which match a set criteria.
Validation can be used to
reduce errors
Validation can't stop errors, but can reduce them. Databases
enable you to use a variety of validation techniques to ensure
that data is 'reasonable, allowable, sensible and within
acceptable boundaries'.
Tables
Allows you to see all of the records stored in the database
Can store many records
A database can contain many tables
Record
Is all of the data or information
about one person or one thing
Each table can contain anything from
a few up to millions or records/rows
Is made up of lots of
individual pieces of
information