Chapter 3 Building Conceptual and Logical Diagrams

Relationship property sheet Joins tab (LDM)

A join is a link between an attribute in a parent entity and an attribute in a child entity (attribute pair) that is defined within a relationship.

A join can link primary, alternate or foreign identifiers, or user-specified attributes in the parent and child entities that are independent of identifier attributes.

Steps To define joins in a relationship:

  1. Double-click a relationship in the diagram to open its property sheet and then click the Joins tab.
  2. Select a key in the Parent Identifier list to create joins on its attributes. If you select <NONE>, the attribute lists are empty and you must specify your own attributes to join.

    The attributes linked by the joins are listed in the Parent Attribute and Child Attribute columns.


    Note   Changing a foreign identifier attribute linked by a join
    You can change the foreign identifier attribute linked by a join by clicking the attribute in the Child Entity list, and selecting another attribute from the list.



  3. [optional] If you selected <NONE> from the Parent Identifier list, click the Parent Attribute column and select an attribute from the list, then click the Child Attribute column and select a child attribute.
  4. [optional] Select the Auto arrange join order check box to sort the list by the identifier attribute order. If this option is not selected, you can re-arrange the attributes using the arrow buttons.
  5. Click OK.

Linking attributes in a primary or alternate identifier

For any relationship you can choose to link a primary or alternate identifier, to a corresponding foreign identifier. When you select an identifier from the Joins tab of the relationship property sheet, all the identifier attributes are linked to matching foreign identifier attributes in the child entity.

Note   Changing a foreign identifier attribute link
A foreign identifier attribute can be changed to link to another parent entity attribute, either within the identifier relationship, or independent of it.

Reuse and Migration option for a selected relationship

You can use the following buttons on the Joins tab to reuse or migrate attributes linked by joins.

Tool Description

Reuse Attributes - Reuse existing child attributes with same code as parent entity attributes.

Migrate Attributes - Migrate identifier attributes to foreign identifier attributes. If attributes do not exist they are created.

Cancel Migration - Delete any migrated attributes in child entity.

 

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