Analyzing Data Stores

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Analyzing Data Stores

As a repository of data used by a current information system, a data store can be permanent or temporary, depending on the system.

In current systems analysis, you identify the data structures along with their parts and associations that fall within the defined scope by examining business data repositories, longer-lived files, and possibly also files that interface or communicate between systems. You should not examine transitory files, such as sort files, in the list of data stores.

The content structure of a data store can vary from the very simple "flat file" to complex databases. Start by noting record types, identifiers, and other non-key fields. The structure of the Purchasing data store is shown in the following table.

Record Type	Identifier	Non-Key Field
Purchase Order	Purchase Order Number	Date Raised By Delivery Notes Total Sub Total Sales Tax
Purchase Order Item	Purchase Order Number Product - Code	Quantity Total Price
Product	Product - Code	Description Item Price
Supplier	Supplier - Number	Name Address

The following illustration shows an Entity Relationship Diagram based on the Purchasing data store structure.

Analyzing Data Stores

Although the entity type SUPPLIER has been identified, the analysis of the data store may not provide enough information to deduce all the relationships needed to compose a fully integrated Entity Relationship Diagram.