Chapter 4 Building Conceptual Data Models

Selecting a data type for a data item

There are two ways to select a data type for a data item.

• Attach the data item 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 a data type You select a standard data type along with a length, a level of precision, and optional check parameters
  
  For more information on attaching a data item to a domain, see section Attaching a data item to a domain.

To select a data type for a data item:

1. Select Model→Data Items to display the list of data items.
2. Click the data item to define.
   
   An arrow appears at the beginning of the line.
3. Click the Properties tool.
   
   or
   
   Double-click the arrow at the beginning of the line.
   
   The data item property sheet opens to the General page.
   
4. 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 appears.
   
   Select the radio button corresponding to the data type you want to apply.
   
   Click OK.
   
   
      Undefined data type
   If you do not want to select a data type immediately, you can choose the <UNDEF> data type.
   
   
5. Type the maximum number of characters for the data type in the Length box.
6. 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.
7. Click OK.
   
   The new data type appears in the list of data items.

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