Controlling uniqueness and reuse of data items

Chapter 3 Building Conceptual Data Models

Controlling uniqueness and reuse of data items

The following model options allow you to control naming restraints and reuse for data items:

Option	When selected	When cleared
Unique code	Each data item must have a unique code.	Multiple data items can have the same code.
Allow reuse	One data item can be an entity attribute for multiple entities.	Each data item can be an entity attribute for only one entity

If you do not select Unique Code, two data items can have the same code, and you differentiate them by the entities that use them. The entities are listed in the Used By column of the list of data items.

Item not visible in list
To make an item visible in a list, click the Customize Columns and Filter tool in the list toolbar, select the appropriate check box from the list of filter options that is displayed, and click OK.

To define code and reuse options for data items:

Select Tools→Model Options to open the Model Options dialog box:

Select or clear the Unique Code and Allow Reuse check boxes in the Data Item groupbox, and then click OK to return to the model.

Error message

The following error message is displayed if you select the Unique Code option, when data items are already sharing a name in the CDM:

Error message	Solution
Unique Code option could not be selected because two data items have the same code: data_item_code.	Assign unique codes to all data items