Transcript unit 16 database systems

UNIT 16 DATABASE
SYSTEMS
Lynda Spencelayh
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Principles of database
systems
Databases are everywhere colleges, dentists,
supermarkets, banks, DVD stores, hospitals,
hotels, gyms, - there are many more examples.
Within each of these organisations the following
information could be store; customers, sales,
products, suppliers, purchasers, Stock,
accounts, VAT.
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These databases are organised in such a
way that data can be easily entered,
stored, edited, deleted and manipulated
to support the activities of the
organisation.
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Advantages
Easy to use
records are easy to access and retrieve
data can easily be manipulated in many
ways
data can be validated to ensure that it is
accurate when input
easy to store
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Disadvantages
Database structures must be carefully
developed to ensure that they work as
efficiently as possible
there are laws that control the use of databases
many people feel that simply too much
information is stored about us
the cost of technology can be prohibitive
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Terminology
An object is something that can be designed,
selected and manipulated Tables, queries,
forms and reports are all examples of objects.
Tables consists of rows and columns, where
the row contains a record and the column
becomes a record field.
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Buttons
The user should be able to carry out all their
tasks from the form.
They can already add a new record and change
data in a record.
You should now add a button to the form to let
them delete a record.
A button is a type of shortcut that can help the
user to work more efficiently. Add a button to
delete records.
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Data entry order
[tab order]
The tab will automatically guide you
around the form
you can change the data entry order
study the handout and change the order
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Query structure
Used to interrogate the data in a database.
This means filtering and sorting the data to
answer questions.
The query uses the data in the table, by
searching the information in the fields and
applying the chosen criteria.
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Queries - single criteria
Equals = this will check whether data is exactly
Less than [<] this can be used with number
Greater than [>] can also be used for dates,
numbers or text.
Not equals - this can be used to find fields that
do not match the data.
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Queries - multiple criteria
You can combine two or more criteria by
using AND, OR, NOT, BETWEEN these are
known as multiple criteria.
Study your mobile phone database
complete activity use a multiple and single
criterion.
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Queries
Wild Cards – Wild cards can be used when:
 You do only remember part of the name
 When you want to find all records which mention a
particular name.
 A star represents any numbers of characters or numbers
 A question mark represents one character or number
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Sorting records
You can sort data via the query in design
view.
You can also sort data directly in the
table.
Simply click on the relevant field and one
of the sorting icons. A to[ascending
order] or Z to A [descending order]
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Reports
A report is a printed record of data in the
database.
There are several benefits of presenting
information in a report rather than just
viewing the data on-screen.
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Reports
It counts the records in the report and displays
the result.
it adds a heading that can be changed by the
user.
It adds the date and time.
It adds a age number
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Reports
 Reports are very useful if you wish to share some of the
information in the database with others in a printed format.
 Reports can be laid out so they are easy to read and
understand
 Reports can be used to select and present exactly the data
that someone needs rather than everything in the database.
 Although reports are intended to be printed as hard copy,
they can also be transferred as electronic documents by
email.
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Layouts
 Columnar layout- each record is laid out with the
fields underneath each other. The labels are placed to
the left of the data. This layout ideal when there is a lot
of data in each record.
 Tabular layout - this arranges the data in a table can
be used for forms and reports if the amount of data in
each record fits comfortably.
 Justified layout- this displays data one record at a
time. The appearance is a formal boxed style. Which
fits neatly across the page, with the labels for each field
above the data. It makes efficient use of space.
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Add buttons to link to
forms and reports
 Improving efficiency - the database should be easy for the
user to use. Normally you will have one main form with
options that link to other forms.
 You can create forms based on any queries you have created
you should decided which ones will be useful to the user.
 Add buttons to the main form that link to these. Remember
a button is a type of shortcut to help the user to work more
efficiently.
 The user may want to print out the data from one of these
forms, so you can add a button that links to the report.
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