USING MICROSOFT ACCESS XP- MANUAL

What is data?
• Data is made up of text, numbers, images and in some cases sounds which can be
processed or stored by a computer. By itself data might not mean very much. In order to
understand it, it needs to be interpreted (or processed) to become information.
• Information is the meaning given to data by the way in which it is interpreted.
• To illustrate the difference, Murray, 15000 and 10 mean little as data. But if we were
able to interpret them as the name of a salesman, Murray, his annual basic salary of
$15,000 and his commission rate of 10%, it would assume more meaning and could be
called information. This is not necessarily the end of the story as this information could
be included in another set of data and used to provide other information. Alternatively,
the same data could be interpreted in another way.
• It is often helpful to think of data as the raw ingredients of a recipe which when
processed and mixed in different amounts by differing techniques produce different
results.

What is a database?

• A simple definition of a database is:
A structured collection of related data about one or more subjects.
In normal daily life we make frequent use of databases, and probably don’t realise it.
Here are a number of simple examples:
- The telephone directory
- Bus or train timetable
- Personal address book
- Filing कैबिनेट

What is a relational database?

• A simple relational database, such as Microsoft Access, is a database which is based on
tables. Each column within a table defines the fields, while each row defines the records.
Different related data can be held in separate tables. For instance information about
suppliers can be held in one table, while information about products can be held in a
separate table.
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5.1.1.2 Understand how a database is organised in terms of tables,
records, fields, and with field data types, field properties.

What is a table?

• A table holds data about a particular item, such as products or suppliers.
What is a record?
• A record is a collection of information which relates to a particular item within your
database table. For instance a record in an address book may consist of the first and
second name of a person, plus their phone number and address details. Each item
within a record is called a field.

What is a field?

• Fields are the individual items which make up a record within your database. In the
example of an address book database, first and second names of your contacts would
both be field names, as would the telephone number.

What is meant by 'Field data types'?

• A field must have a specific data type format. We will see more about this later, but for
now the illustration shows you the data types which are available within Microsoft
Access, including Text, Number, Currency etc.

What is meant by 'Field properties'?

• Each field has a range of field properties associated with it. For instance the Field Size
(set to 50 in the example shown), means that the field will hold a maximum of 50
characters.
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Other properties include items such as data validation, which means that the sort of
information which is being entered into a field makes sense!
5.1.1.3 Understand what a primary key is.

What is a primary key?

• Primary keys uniquely identify each record in your table and provide the following
advantages:
- An index is automatically created for the primary key.
This speeds up data retrieval and sorting.
Also, the primary key is often used in establishing relationships.
- Records in a form or Datasheet are displayed in primary key order.
- Duplicate records are not allowed. Therefore all records are unique
- A primary key can be made up of one or more fields.
5.1.1.4 Understand what an index is.

What is an index?

• An index allows Microsoft Access to work faster when finding and sorting records. They
work in a similar way to the way you would use an index in a traditional book, i.e. Access
uses the index to find the location of the required data. Indexes can be created using a
single field, or using multiple fields.
5.1.1.5 Understand the purpose of relating tables in a database.

Why relate tables?

• When using Access you normally set up a number of tables, such as Customers,
Products, Orders, Employees etc. The next stage is to define relationships between
these tables so that the information within each table can be linked with the information
in the other tables. Once these table relationships are defined we can create queries,
forms and reports to display information which is actually spread across several tables.
5.1.1.6 Understand the importance of setting rules to ensure
relationships between tables are valid.
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Design and document your database!
• It is extremely important to spend time designing your database as time spent here will
often pay dividends later on in the process, as you know where you are going and what
you are trying to do.

How do you know if you’ve got there if you don’t know where you are going?

Questions to ask yourself
• When setting out on the difficult design stage of producing the database there are a
number of questions which you should ask yourself or your user.
What do I want?: You must first establish why you require your database and what you
expect to get from it. It is most important to define your output needs first.
Mistakes are often made because people try to decide what to put into their database
before they know what they want from it.
What have I got?: Knowing what you want then allows you to look critically at what data
you have and make decisions as to how it should be structured in terms of fields and
tables.
What do I need to do?: This question asks you to look at any manipulation you need to
carry out in order to achieve your information output: searches, sorts, and calculations.
Define your needs
• In order to clarify your needs it is often useful to draw a simple diagram and/or write a
short narrative. If the database is being designed for others, show them your
sketch/narrative and use it to check your understanding of their requirements.
Example:
C.C.Toys is a retailer of toys for children of all ages. It buys its toys from a number of
suppliers. It employs four staff. The store is laid out according to themes under a number
of categories (e.g. Soft toys, Games Software etc.). Orders to suppliers can be for either
single or multiple products.
The illustration below shows the tables needed for C.C. Toys.
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