Chapter 4 Building Conceptual Data Models

Selecting a data type for an entity attribute

There are two ways to select a data type for an entity attribute:

• Attach the entity attribute to a domain The domain dictates a standard data type, a length, and a level of precision, as well as optional check parameters.
• Manually select the data type You select a standard data type along with a length, a level of precision, and optional check parameters

To select a data type for an entity attribute:

1. Double-click an entity in the diagram to display the entity property sheet.
2. Click the Attributes tab to display the corresponding page.
   
   It lists entity attributes associated with the entity.
3. Click the Entity attribute to define.
   
   An arrow appears at the beginning of the line.
4. Click the Properties tool.
   
   or
   
   Double-click the arrow at the beginning of the line.
   
   The entity attribute property sheet opens to the General page.
   
5. Select a data type from the Data Type dropdown listbox.
   
   or
   
   Click the Question mark button at the end of the Data Type dropdown listbox.
   
   A list of standard data types supported by PowerDesigner appears.
   
   Select the radio button corresponding to the data type you want to apply.
   
   
      Undefined data type
   If you do not want to select a data type immediately, you can choose the <UNDEF> data type.
   
   
   
   
6. Type the maximum number of characters for the data type in the Length box.
7. If the data type can include values that take a decimal point, type the number of places after the decimal point in the Precision box.
8. Click OK.
   
   You return to the Entity attributes page. The change of data type appears in the list of entity attributes.

Copyright (C) 2005. Sybase Inc. All rights reserved.