The
Design Phase is the second phase in system development. It refers to the
planning of the system design.
GUIDELINES
FOR DESIGNING A DATABASE:
Choose data
Choose
the neccessary data you need to store in the database. For example, in the
School Resource System, the necessary data are Author, Book, Category and
Publisher.
Ensure table contains the necessary data
In
this School Resource System, there are four Tables involved, namely Author,
Book, Category and Publisher.
From
the analysis, the system developers found out that:
An
author can have one or more books.
A
publisher has one or more books.
A
category has many books.
Determine field
You
need to ensure Tables contain the necessary data.
You
need to determine what fields to include and the suitable data type format for
those fields.
Author
Table consists of AuthorID and AuthorName.
Book
Table consists of BookID, BookTitle and BookPrice.
Category
Table consists of CategoryID and CategoryName.
Publisher
Table consists of PublisherID and PublisherName.
These
are the technical plans we designed during the Design Phase.
In the Design Phase, the system developers will
seek to provide input interface and output interface.
System developers will provide an input interface
where the user can do data entry.
The user can also retrieve information from a
database using an output interface.
ENTITY
RELATIONSHIP DIAGRAM
Entity
Relationship Diagram (ERD) is one of the diagrams that show how Tables are
organised and related to one another.
There
are two symbols used in an Entity Relationship Diagram.
In
the School Resource System, system developers can use the Entity Relationship
Diagram to describe all Tables and their fields.
EXTENSION
: MOCKUP
A
mockup is a sample of the input or output that contains actual data.
A
mockup is needed when handling a big database program so that the system
developer and target user understands the system better.
The system developers show mockups to users for
their approval.
It
is important to involve users during input and output design stages because
users finally will work with those designs.
Users
must give their approval on all inputs and outputs before system developers
proceed with database design. A mockup ensures input and output designs meet
the needs of users.