Gathering data requirements

When is the technique applicable

If gathering requirements for an IT system then inevitably some of the requirements will mean storing data or doing something with data.  A logical data model can be a technique for gathering these.  It is very useful because it enables a diagram to be drawn up which can be discussed to improve the understanding of the data relationships.  A table also known as a data dictionary can then be used to gather further information about the data itself.

This technique is the most useful for gathering data requirements in the following circumstances:

• The system is completely new
• The stakeholders are using lots of complex terms and specialised business terms making it difficult to understand what they are talking about
• The stakeholders are interchangeably using different terms that could mean the same thing
• There aren’t clear examples available to show the data inputs or outputs
• It isn’t clear which of the data mentioned are entities or attributes or how they relate to each other

What is the expected outcome/benefit of using it?

• Enables data requirements to be grouped together in a logical structure and an understanding of how the data relates to each other.
• Ensures agreement of consistent terminology

How to use/apply it

A class or entity is a group of data with connected characteristics.  The different characteristics are known as attributes.

Each time a different data requirement is mentioned write it on a white board or flip chart.  Check it hasn’t been previously included and establish the relationship between the other data requirements written.  If it has a one to one relationship with a previous data requirement group it together as it belongs in one entity otherwise separate it out and establish whether the relationship is one to many or many to many etc.

Worked examples of when/how it has been used.

See diagram below.  This is an example using a class diagram and using syntax from UML.  There are similar techniques with slightly different syntaxes.

The below is an example from the article drilling down solution requirements into more detail.  In it was a requirement to allow an employee to book holiday through the companies intranet.  The entities identified were employee and holiday.  This showed the relationship as an employee could book zero to many holidays but a holiday was applicable to just one employee.

Discussing the relationships between the entities could uncover further requirements about the data.  For example the above would mean that there is only one employee record and that the number of days entitled would have to be overridden each year.  Another problem with the above relationship is that it means that an employee could only book holiday in that current year so could not book for the next year.  If this wasn’t the case then an additional entity would need to be added to keep an historical record each year.  After understanding more about what is needed from the data the diagram may be changed to the following.

Holiday entitlement has now been added to keep a record of holiday entitlement each year and to allow future years to be booked.

In addition to the diagram a table is required to understand more detail about the data requirements.

Employee

Description:  Employees at the company who are permanent or FTC contractors.

Attribute Name	Description
Employee name	The name of the employee	Mandatory / Optional	Mandatory
		Type	Alpha numeric
		Length	30
		Format
		Validation
		Default
		Example	Bob Hoskins
Team	The team the employee works in	Mandatory / Optional	Mandatory
		Type	Alpha numeric
		Length	30
		Format
		Validation
		Default
		Example	Change team
Date started company	The date the employee started at the company	Mandatory / Optional	Mandatory
		Type	Date
		Length	10
		Format	Dd/mm/yyyy
		Validation
		Default
		Example	23/04/2001
Date left company	The date the employee left the company	Mandatory / Optional	Optional
		Type	Date
		Length	10
		Format	Dd/mm/yyyy
		Validation
		Default
		Example	01/10/2007

 

 

Holiday entitlement

Description:  The holiday entitlement of each employee

Attribute Name	Description
Holiday year	The year of the holiday entitlement for each employee who has started at the company and not left.	Mandatory / Optional	Mandatory
		Type	Alpha numeric
		Length	4
		Format	Yyyy
		Validation
		Default
		Example	2017
No of days entitled	The number of days an employee is entitled to in the current year.  This is a calculated field depending upon the number of years the employee has been with the company.	Mandatory / Optional	Mandatory
		Type	Alpha numeric
		Length	30
		Format
		Validation	Less than 5 years – 20 days 5-10 years – 25 days Greater than 10 years – 30 days
		Default	20 days
		Example	20 days
No of days left	The number of days the employee has left for a holiday year.  This is a calculated field taking into account the number of holidays approved in a holiday year.	Mandatory / Optional	Mandatory
		Type	Alpha numeric
		Length	30
		Format
		Validation	No of days entitled – holiday approved in that year
		Default
		Example	10

 

Holiday

Description:  The number of holidays booked per employee

Attribute Name	Description
Date from	The date from which the employee wishes to book holiday.	Mandatory / Optional	Mandatory
		Type	Date
		Length	10
		Format	Dd/mm/yyyy
		Validation
		Default
		Example	12/09/17
Date to	The date the employee wishes to book holiday to.	Mandatory / Optional	Mandatory
		Type	Date
		Length	10
		Format	Dd/mm/yyyy
		Validation
		Default
		Example	17/09/17
Number of days	To be automatically calculated to store the number of days being booked as a result.	Mandatory / Optional	Mandatory
		Type	Alpha numeric
		Length	30
		Format
		Validation	No of working days between date from and date to
		Default
		Example	10
Manager name	The names of the manager approving the holiday	Mandatory / Optional	Mandatory
		Type	Alpha numeric
		Length	30
		Format
		Validation
		Default
		Example	Bob Hope
Team	The name of the team the manager is from.	Mandatory / Optional	Mandatory
		Type	Alpha numeric
		Length	30
		Format
		Validation
		Default
		Example
Date approved	The date the holiday was approved by the manager	Mandatory / Optional	Mandatory
		Type	Date
		Length	10
		Format	Dd/mm/yyyy
		Validation
		Default
		Example	10/09/17

Using this approach is a technique for understanding the data requirements.

Thoughts? Questions? Please share in the comments.

 

If you have found this article useful then you might like my book – The Business Analysis Handbook – Techniques and Questions for better Business Outcomes.  The book is available from www.koganpage.com and all major print and e-book retailers.