DEFINE FIELDGROUP command

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Summary

Status

Available as of Model 204 release 7.5

Privileges

Any user

Function

To establish the contents of a field group, including the fields and field groups associated with the field group being defined.

Syntax

DEFINE FIELDGROUP FieldGroupName [WITH FIELDGROUP OuterGroupName]

Where:

  • FieldGroupName specifies the name of the field group you are defining.

    A field group name must be unique among field group names, and it cannot have the same name as any field.

  • OuterGroupName specifies the name of another field group previously defined. The field group being defined is nested under the OuterGroupName.

For general syntax and usage notes that apply to all forms of the DEFINE command, see DEFINE command.

Adding fieldgroup contents

The WITH FIELDGROUP clause identifies a field group that is already defined. For example, to define a field group MAKE_MODEL containing fields MAKE and MODEL:

DEFINE FIELDGROUP MAKE_MODEL DEFINE FIELD MAKE WITH FIELDGROUP MAKE_MODEL AND ORDERED CHARACTER DEFINE FIELD MODEL WITH FIELDGROUP MAKE_MODEL

To define a field group within a field group:

DEFINE FIELDGROUP BIRDS WITH FIELDGROUP VERTEBRATES

Field considerations

  • Fields defined in a field group definition follow the syntax rules described in the DEFINE FIELD command.
  • Field definitions must follow the definitions of their containing field group. It is then easier to add fields later to an already defined field group, for example:

    DEFINE FIELD YEAR WITH FIELDGROUP MAKE_MODEL

  • The keyword AND on field definitions means that a field group name can contain blanks, just like a field name.

    To separate a field group name from subsequent field attributes, you must use the AND keyword:

    DEFINE FIELD COLOR WITH FIELDGROUP MAKE_MODEL AND ORDERED CHARACTER

    The AND is unnecessary if the FIELDGROUP FieldGroupName clause is the last field attribute:

    DEFINE FIELD COLOR WITH ORDERED CHARACTER FIELDGROUP MAKE_MODEL

    Note: The MAKE_MODEL field group must be defined before defining the field(s) and/or field group(s) that belong with it.

  • Once you define a field you cannot move it into or out of a fieldgroup using a REDEFINE command. You must delete the field and relocate it by defining it again, locating it where you want it.

Attribute considerations

A field in a field group cannot have the OCCURS or INVISIBLE attribute. You can assign any other attributes you choose, paying attention to those that conflict with each other.

The default attribute for frequency of occurrence for fields in a field group is EXACTLY-ONE, whereas the default for individually defined fields is REPEATABLE. Of course, you can declare a field inside a field group as REPEATABLE, as well as AT-MOST-ONE.

The REPEATABLE and AT-MOST-ONE field attributes have different behavior for fields inside a field group. The REPEATABLE attribute means that the field can have more than one occurrence inside a field group occurrence, whereas the AT-MOST-ONE attribute means that the field can have only a single occurrence inside a field group occurrence.

Nested field groups

Nested field groups are limited to 16 levels. The syntax for nesting is designed as follows:

DEFINE FIELDGROUP VERTEBRATES DEFINE FIELDGROUP BIRDS WITH FIELDGROUP VERTEBRATES DEFINE FIELDGROUP PARROTS WITH FIELDGROUP BIRDS DEFINE FIELDGROUP OWLS WITH FIELDGROUP BIRDS DEFINE FIELDGROUP REPTILES WITH FIELDGROUP VERTEBRATES DEFINE FIELDGROUP SNAKES WITH FIELDGROUP REPTILES

See also