Working with Data Models › Data Types and Data Type Standards

Data Types and Data Type Standards

A data type is a predefined set of characteristics for an attribute or column that specifies field length, acceptable characters, and optional and required parameters. For example, the data type Char(18) specifies that the column can store up to 18 alpha and numeric characters.

By default, a data type is applied to every attribute in a logical model and to every column in a physical model. In the logical model, the data type is determined by the domain from which the attribute inherits its properties or from the data type that you assign. In the physical model, the data type is determined by the default value that is specified by the target server or the data type that you assign.

Considering the large quantity of attributes or columns a data model usually has, it is tedious to assign and maintain consistency of data types manually. The DSM Option Editor helps you easily assign and maintain data types in a model.

Create data type standards so that everyone in your organization uses data types consistently.

When you create a DSM Option object, it is preloaded with default logical data types. Use the DSM Options Editor to create data types and mappings. You can create multiple DSM Option objects but you can apply only one of them to the model.

You can assign data types in any of the following scenarios:

• Deriving a physical model from a logical model, or switching from a logical model to a physical model. A physical data type is automatically assigned to each column based on the data type assigned to the corresponding attribute.
• Deriving a physical model from a physical model. The corresponding data type for the target database is automatically assigned.
• Migrating from one version of a database to a newer version, or changing the target database. You are prompted you to verify if you want to convert data types. When you convert the data types, the corresponding data type for the target database is automatically assigned.
• Creating a physical model by reverse engineering from a database or script file. Information from the database or script file is extracted, and a physical data type is automatically assigned to each column.