Identifying application data

Two important aspects of application design are identifying the application data and describing the data that a particular business process requires.

One of the steps of identifying application data is to thoroughly understand the processing the user wants performed. You need to understand the input data and the required output data in order to define the data requirements of the application. You also need to understand the business processes that are involved in the user's processing needs. Three of the tasks involved in identifying application data are:

Listing the data required by the business process
Naming the data
Documenting the data

When analyzing the required application data, you can categorize the data as either an entity or a data element.

Definitions: An entity is anything about which information can be stored. A data element is the smallest named unit of data pertaining to an entity. It is information that describes the entity.

Example: In an education application, students and courses are both entities; these are two subjects about which you collect and process data. The following table shows some data elements that relate to the student and course entities. The entity is listed with its related data elements.

Table 1. Entities and data elements
Entity	Data elements
Student	Student Name
Student	Student Number
Course	Course Name
	Course Number
	Course Length

When you store this data in an IMS database, groups of data elements are potential segments in the hierarchy. Each data element is a potential field in that segment.