RELATIONAL DATABASES
A database allows large amounts of data to be stored in an organised way. Data can be interrogated to
obtain information that can be used to help decision-making processes.
Students construct an information system based on a relational database that stores data efficiently in
normalised tables, minimises file size, and reduces unnecessary data entry. The outcomes will use
calculations and display dynamic information, such as a list of today’s appointments or a record of
services for a customer. Navigation through the system will be made user-friendly by the setting of
properties, the implementation of features, the writing of scripts, and in the design and finished layout of
the menu and forms and reports. Students use the problem-solving approach of the systems
development life cycle to build a system.
Focus
Students investigate how database management systems are used by individuals, organisations, and
communities by considering the following:

A relational database uses data to produce meaningful information such as:
tomorrow’s appointments in a hairdressing salon for an individual hairdresser;
the venues a band has played at this year;
the rooms booked for next weekend in a motel;
the videos available for rental;
the positions of sports teams on a ladder.

The information obtained from a database management system helps individuals, organisations, and
communities to make decisions such as:
how often a movie will be screened in a cinema complex;
how many staff will be needed at different times in a video store;
on which flights special deals will be offered and how many seats will be released;
how successful an advertising strategy is, based on total sales generated.

Database management systems are the core of many information systems.

A database management system is used to produce meaningful information for a user.

A relational database stores data in a way that reduces data redundancy.

A user interrogates a database to obtain information.

Data is processed and manipulated into information in a number of ways.

Data can be processed by applying criteria, sorting, and/or grouping.

Data can be manipulated by the use of operands and functions.
Design
Students develop an understanding of how data is stored and defined in a relational database and, by
applying knowledge and skills, propose a design. Students consider the following key questions and
concepts:
How is data stored in a database management system?
 A database management system uses a relational model.

Data is stored in fields and entities/records.

When grouping data into tables (normalisation), students should consider the following:
The need to minimise the duplication of data.
A key consists of one or more fields that uniquely identify a record in a table.
Non-key fields are dependent on the key.
Non-key fields are not dependent on another field (except a key).

When relating tables, students should consider the following:
Tables can be referred to as source, transaction, or reference/lookup.
The links between tables are identified as one-to-one, one-to-many, or many-to-many.
So that two tables can be related, a key field needs to be identified and justified from other fields in
the table.
Tables are linked by joining the key from the table on the one-side to the appropriate field on the
many-side.
The solving of a many-to-many relationship by adding a transaction/junction table.
How is data defined?
 Data can be allocated a type dependent on its use in a system.


Data is controlled and limited by application of data size, required values, validation rules, default
values, and input masks.
Data is entered into a table.

Integrity of data is essential for accuracy.

Data is entered according to referential integrity concepts.

A data dictionary includes field names, types of data, sizes, key(s), required values and the appropriate
validation rules and text messages, default values, formats, and input masks.

A table relationship diagram shows the tables, their fields, the key fields, and the type of relationship
between the tables that the fields link.
Development
Students explore the way data can be manipulated and, by applying knowledge, skills, and problemsolving techniques, create a relational database. Students consider the following key questions and
concepts:
How is data accessed and manipulated?
 Data is entered and edited through a finished data-entry form/layout.

Data-entry processes can be made user-friendly by the use of a form that includes some of the
following features:
Pop-up or lookup lists, with sorted data. A lookup list may include data from more than one table,
entities that are available, or new source data that has been added.
A form/sub-form layout (portal).

Information is produced by designing outcomes that are achieved by using criteria (one or more) and
Boolean operators.

Outcomes can be made dynamic by the use of:
functions in criteria (e.g. today’s date);
input/parameter criteria via a dialog box and/or via selecting a value from a list.

Calculated fields are new fields created by using existing field(s) and operand(s) or function(s).

Statistical information can be obtained in a query by grouping and using sum, count, min, max, or
average.

An outcome can be based on data from a table or a query.

Information is made user-friendly by designing reports with a finished layout.

Reports include grouping, sorting, and summary and grand summary statistics such as sum, count,
min, max, or average.

A relational database is accessed through a menu and its related scripts (coding/macros). This is
enhanced by setting properties of forms and controls.

The interface can be made user-friendly by considering the following features:
The size of the form when opened.
Changes to the layout or arrangement of the existing interface when another form is opened or
closed.
A form-based selection list to open a data-entry screen for the selection.
Scroll bars, non-standard navigation buttons, control tip text, status bar text, user-friendly error
messages, and online help.
How can outcomes be substantiated?
 Records can be substantiated by following data links between tables.
 A database model is reviewed and critiqued for effectiveness and efficiency.
Social Responsibility
Students develop an understanding of their responsibility in using and developing relational databases,
and the impact of databases on society, by critically evaluating and responding to related issues.
Students consider the following key questions and concepts:
What are the responsibilities of a database developer?
A database developer should:
 apply recommended practices and conventions that include:
retaining versions of the file and following effective backup procedures so that the file can be
recovered in case of errors in design, data deletion, corruption, or virus infection;
using antivirus software to protect development files;

consider the following in the implementation of a database:
Secondary storage media are determined by considering present and future requirements of the data
for a database.
Backing up a database enables data to be recovered if it is deleted or becomes corrupted.
Data should be protected from accidental or deliberate erasure through virus infection, hardware or
software failure, theft, damage to equipment, unauthorised access, hacking, and so on.
Privacy legislation determines responsibilities for storing, using, and accessing data in a database.
The privacy of stored data can be protected by the implementation of security measures.
What is the impact of databases on society?
 The use of databases has changed the work practices, procedures, and decision-making processes of
individuals, organisations, and communities.

New practices are supported by the speed at which information can be produced and distributed from a
database and integrated hardware (e.g. SMS messages).

Accessibility of data stored centrally allows more users to use the data as a basis for their conclusions
and to make predictions.

As users become more knowledgeable about the capability of a database, the demand for data and
information increases.

Data may be collected for economic, community, educational, marketing, and research purposes.
Information should be used in a meaningful, responsible, and ethical way.

Data is protected by privacy legislation and, in some cases, by social and cultural protocols. Permission
may need to be sought from the owner(s) of the data for its collection, use, and storage.