Identifying Requirements (DDD) (SQA National 5 Computing Science): Revision Note

End-user requirements (DDD)

What are end-user requirements?

• End-user requirements describe what the user needs to achieve with the database

• They focus entirely on the user’s tasks and goals

• Written from the point of view of the user

• Describe what the user wants to achieve using the database

• Do not mention tables, fields, validation or technical detail

• Usually gathered by interviewing or observing the users

• Used to understand what the final system must allow the user to do

Example end-user requirements

• These examples focus only on tasks and goals

• No tables, no fields, no SQL, no validation

• These requirements never mention how the database will achieve the task

Functional requirements (DDD)

What are functional requirements?

• Functional requirements describe the processes and data the system must contain to satisfy the end-user needs

• They define the technical features, data, and processes the system must include

• Used to design and build the database and check if it is fit for purpose

Key aspects of database functional requirements

Data structures

• This describes how the database is organised

• It specifies tables and relationships

• Example:

  • The database will have two tables, Cars and Branches, linked using branchID as a foreign key

Data fields

• Specify attributes

• They describe the exact pieces of data the system must record

• Example:

  • The system must store carMake, carModel, colour, fuelType, price and mileage

Processing

• This describes the operations the database must carry out

• Specifies required queries, sorts, filters

• Example:

  • The system must run simple and complex queries to search for cars using multiple criteria

  • The system must sort results in ascending order of price

Validation and constraints

• Specifies control measures on data entry

• They include range checks, restricted choice, length checks and presence checks

• Validation protects data quality and prevents invalid entries

• Example:

  • The price field must use a range check between 0 and 100000

  • soilType must be restricted choice (Clay, Loam, Peat or Sandy)

Example functional requirements

• These are technical

• These requirements directly define the data dictionary and SQL needed during implementation