Chapter 3 Building Physical Diagrams
You can access column properties from a table property sheet:
| Property | Description |
|---|---|
| Name | The name of the item which should be clear and meaningful, and should convey the item's purpose to non-technical users |
| Code | The technical name of the item used for generating code or scripts, which may be abbreviated, and should not generally include spaces |
| Comment | Descriptive label for the column |
| Stereotype | Sub-classification used to extend the semantics of an object without changing its structure; it can be predefined or user-defined |
| Table | Table which contains column |
| Data type | Form of the data corresponding to the column, such as numeric, alphanumeric, boolean, or others |
| Displayed | When selected, allows the display of selected column in list of columns, otherwise the column is grayed |
| Length | Maximum length of the data type |
| Precision | Maximum number of places after the decimal point |
| Identity | When selected, indicates that the data is auto-incremented (not available for all DBMS) |
| Domain | Name of the associated domain |
| Computed | When selected, designates that the column is computed from an expression using values from other columns in the table (not available for all DBMS) |
| Primary key | When selected, designates a column whose values uniquely identify a row in the table |
| Foreign key | When selected, designates a column that depends on and migrates from a primary key column in another table |
| Mandatory | When selected, indicates a column that must be assigned a not null value |
| With default | When selected, indicates if a default value is assigned to the column when a Null value is inserted (not available for all DBMS) |
A column also includes the following properties:
| Property | Description |
|---|---|
| Detail | Column fill parameters. These determine the percentage of column entries for which a null value is permitted, and the percentage of column rows that contain unique values.
Test data parameters. You can select a test data profile from the list available using the dropdown listbox Computed Expression. You can enter a computed expression for the column |
| Standard checks | Standard check parameters |
| Additional checks | SQL expression defining a check parameter |
| Options | Physical options for columns. These are DBMS-specific |
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