The relationship that MultiValued attributes have to one another can be further defined by a Controlling attribute and one or more related Dependent attributes.
Controlling and Dependent attributes identify a unit of related data. A Dependent attribute cannot be displayed in a report unless the related Controlling attribute is also included. This is because the data in Dependent attributes might otherwise have no meaning. For example, it would make little sense to display the number of books ordered unless the books themselves were also identified in the report.
Line 4 of an Attribute Definition item determines whether an attribute is Controlling, Dependent, or neither. For example, the Attribute Definition item for PRODUCT in the ORDERS dictionary defines this attribute as Controlling and links it to Dependent Attribute 4 (QTY):
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>LIST-ITEM DICT ORDERS 'PRODUCT' PRODUCT 001 A 002 3 003 PRODUCT 004 C;4 005 006 007 008 009 L 010 5 |
The Attribute Definition item for QTY defines this attribute as Dependent and links it to Controlling Attribute 3 (PRODUCT):
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QTY 001 A 002 4 003 QUANTITY 004 D;3 005 006 007 008 009 R 010 3 |
See Also