Indicating data type, length, and precision in a CDM

Chapter 4 Building Conceptual Data Models

Indicating data type, length, and precision in a CDM

Length and precision

The properties length and precision do not apply to all data types. Depending on data type, length may indicate a maximum or a fixed number of characters.

In the list of available data types, a variable indicates where you have to type a length or precision, as follows:

Variable	Replace with
%n	Length
%s	Length with precision
%p	Decimal precision

For example, if you are using Sybase Adaptive Server Anywhere and you choose the data type

char(%n)

, you can choose a length of ten by typing

char(10)

Undefined data type

All target DBMS allow you to select the <undefined> data type. The <undefined> data type indicates which domains remain without data types. If an <undefined> data type is present when you generate your database, it is replaced by the default data type for your database.