Understanding Your Data Model › Using Relations › Adding Virtual Fields to File-to-file Relations

Adding Virtual Fields to File-to-file Relations

The fact that a relation exists between two files means that, given a record from one file, it is possible to look for a corresponding record on the other file in order to obtain related data items.CA 2E allows you to specify which data items are to be obtained through a file-to-file relation by allowing you to specify virtual fields. A virtual field is a field that is present logically in a view of a file although it physically resides in another file.

Virtual fields can be specified on the following relations:

• Owned by
• Refers to
• Extended by

FIL         Order line              REF     Refers to       FIL     Product         REFT

                                            VRT     Product name    XT

where:

Refers to—Represents a File to file relation

Product—Represents a CA 2E file containing field

Product name—Represents a virtual field name

Virtual fields can be defined only in one direction on the relation. In CA 2E, the file that can contain virtual fields is the file where the relation is defined. For example, Division is Owned by Company. Fields from the Company (owning file) can be virtualized to the Division (owned file). Fields from Division cannot be virtualized to Company. Division contains the virtual fields. Division is where the Owned by relation is defined.

A virtual field may itself be a virtual field on the referenced file.

You can specify virtual fields for relations using the Virtual Field Entries panel.

The example below shows how virtual fields are added to a relation:

• On the Order file we could have the Customer name as a virtual field:

FIL    Order   CPT     Known by        1 FLD   Order code      REF

FIL  Order   CPT     Has             2 FLD   Order date              CDE

FIL  Order   CPT     Has             3 FLD   Order status            TXT

FIL  Order   CPT     Refers to       4 FIL   Customer                        

                                          VRT   Customer name

• On the Order Detail file we could have both the Order information, including the Customer name and the Product name as virtual fields:

FIL  Order detail    CPT     Owned by        1 FLD   Order           REF

       VRT   Order date      DT#

       VRT   Order status    STS

       VRT   Customer code   CDE

       VRT   Customer name   TXT

FIL  Order detail    CPT     Known by        2 FLD   Order line no   CDE

FIL  Order detail    CPT     Has             3 FLD   Order quantity  QTY

FIL  Order detail    CPT     Refers to       4 FIL   Product REF

                                               VRT   Product name    TXT

• This would result in the following entries on the files:

See the chapter "Maintaining Your Data Model" for more information on how to add virtual fields to a relation.