Reference Properties

The General tab contains the following properties:

Property	Description
Name/Code/Comment	Identify the object. The name should clearly convey the object's purpose to non-technical users, while the code, which is used for generating code or scripts, may be abbreviated, and should not normally include spaces. You can optionally add a comment to provide more detailed information about the object. By default the code is generated from the name by applying the naming conventions specified in the model options. To decouple name-code synchronization, click to release the = button to the right of the Code field.
Stereotype	Extends the semantics of the object. You can enter a stereotype directly in this field, or add stereotypes to the list by specifying them in an extension file.
Parent table/ Child table	Specify the parent table (which contains the primary or alternate key or a user-selected column) and the child table (which contains the foreign key or a user-selected column) linked by the reference. Use the tools to the right of the Parent table field to create, browse for, or view the properties of the currently selected table.
Parent role/ Child role	Specify the roles of the parent and child tables in the reference (for example `Contains` and `Is contained by`.
Generate	Specifies to generate the reference in the database.
Keywords	Provide a way of loosely grouping objects through tagging. To enter multiple keywords, separate them with commas.

Joins Tab

The Joins tab lists the joins defined between parent and child table columns. Joins can link primary or alternate and foreign keys, or any user-specified columns.

Note: You can control the default joins created using the Default link on creation and Auto-migrate columns model options (see Automatic Reuse and Migration of Columns).

On this tab, you can either:

Select a key from the parent table in the Parent key field on which to base the join to autopopulate the list with its associated parent and child columns. If necessary, you can modify the specified child columns.

Specify <None> in the Parent key field and specify your own column pairs on which to base the join using the following tools:

Tool	Description
	Reuse Columns - Create a join by matching parent and child columns that share the same code and data type.
	Migrate Columns - First specify columns in the Parent Table Column column and then click this tool to migrate them to foreign key columns in the child table. If the columns do not exist in the child table, they are created.
	Cancel Migration - Remove any columns migrated to the child table.
	Insert/Add a Row - Inserts a row before the selected row in the list or at the end of the list to specify another column to join on.

Note: Select the Auto arrange join order check box to sort the list by the key column order or deselect it to re-arrange the columns using the arrow buttons. If this option is not available, to enable it, add the EnableChangeJoinOrder item to the Reference category in the DBMS definition file and set the value to YES (see Customizing and Extending PowerDesigner > DBMS Definition Files).

Integrity Tab

Referential integrity governs data consistency between primary or alternate keys and foreign keys by dictating what happens when you update or delete a value or delete a row in the parent table. The Integrity tab contains the following properties:

Property	Description
Constraint name	Specifies the name of the referential integrity constraint. Maximum length is 254 characters. If you edit this name, the User-defined button will be depressed. To return to the default name, click to release this button.
Implementation	Specifies how referential integrity will be implemented. You can choose between: Declarative- Referential integrity constraints are defined for particular references. When the reference is generated the target DBMS evaluates the reference validity and generates appropriate error messages. Trigger - Referential integrity constraints are implemented by triggers based on the integrity constraints defined in the reference property sheet. The trigger evaluates reference validity and generates appropriate user-defined error messages.
Cardinality	Indicates the minimum and maximum number of instances in a child table permitted for each corresponding instance in the parent table. The following values are available by default: 0..* - A parent can have zero or more children. 0..1 - A parent can have zero or one children. 1..* - A parent can have one or more children. 1..1 – A parent must have exactly one child Alternately, you can enter your own integer values in one of the following formats (using `*` or `n` to represent no limit): `x..y` - A parent can have between x and y children. For example: `2..n` – There must be at least 2 children. `x` - A parent can have exactly x children. For example: `10` - There must be exactly 10 children. `x..y, a..b` - A parent can have between x and y or between a and b children. For example: `1..2, 4..n` – There must be one, two, four or more children.
Update/Delete constraint	Specifies how updating a key value in the parent table will affect the foreign key value in the child table. Depending on the implementation and DBMS, you can choose between: None - No effect on the child table. Restrict - Values in the parent table cannot be updated or deleted if one or more matching child values exists. Cascade - Updates or deletions of parent table values are cascaded to matching values in the child table. Set null - Updates or deletions of parent table values set matching values in the child table to NULL. Set default - Updates or deletions of parent table values set matching values in the child table to the default value.
Mandatory parent	Specifies that each foreign key value in the child table must have a corresponding key value, in the parent table.
Change parent allowed	Specifies that a foreign key value can change to select another value in the referenced key in the parent table.
Check on commit	[SQL Anywhere® only] Verifies referential integrity only on commit, instead of after row insertion. You can use this feature to control circular dependencies.
Cluster	Specifies that the reference constraint is a clustered constraint (for those DBMSs that support clustered indexes).