Systems Life Cycle: Design
File/Data Structures
- Field length: number of characters allowed in a field
- Field name: an identifier for the field in the data structure
- Data type: specifies the kind of data that can be stored in a field, e.g. text, numbers, dates
- Coding of data: using codes to represent data, e.g. M for male, F for female
Input Formats
- Data capture forms: designed to collect data from users in a structured format
- Consider a user-friendly layout, clear instructions, and appropriate data fields
Output Formats
- Screen layouts: how information is presented to users on a screen
- Report layouts: how information is organised in a printed or digital report
- Consider readability, visual appeal, and efficient use of space
Validation Routines
- Range check: ensures data is within a specified range of values
- Character check: ensures data contains only allowed characters
- Length check: ensures data is of a specified length
- Type check: ensures data is of the correct data type
- Format check: ensures data conforms to a specific format
- Presence check: ensures data is present and not left blank
- Check digit: a digit added to a number to verify its accuracy
Exam Tip
- In the design stage of the Systems Life Cycle, focus on creating clear, user-friendly input formats and output formats. Additionally, make sure to implement appropriate validation routines to ensure data accuracy and completeness.
Worked example
Carlos is designing a new computer system to replace an existing system. Tick four items which will need to be designed.
[4]
| Tick | |
| Inputs to the current system. | |
| Data capture forms. | |
| Report layouts. | |
| Limitations of the system. | |
| Observation methods. | |
| Improvements to the system. | |
| User and information requirements. | |
| Validation routines. | |
| Problems with the current system. | |
| File structure. |
| Tick | |
| Inputs to the current system. | |
| Data capture forms. | χ |
| Report layouts. | χ |
| Limitations of the system. | |
| Observation methods. | |
| Improvements to the system. | |
| User and information requirements. | |
| Validation routines. | χ |
| Problems with the current system. | |
| File structure. | χ |
