TFieldDefs = class(TDefCollection)
class PASCALIMPLEMENTATION TFieldDefs : public TDefCollection
TFieldDefs holds the field definition (TFieldDef) objects that represent the physical fields underlying a dataset.
Datasets use TFieldDefs to manage the field definitions they use to create field objects that correspond to fields in a database table. Every field definition listed by TFieldDefs has a corresponding TField object, but not all TField objects have a corresponding field definition. For example, calculated fields do not have field definitions.
TTable and TClientDataSet objects also use TFieldDefs when creating a new table.
With object field types, such as TADTField and TArrayField, there are two ways to represent the field definitions: hierarchically or flattened. When represented hierarchically, object field definitions contain a set of child definitions for the constituent subfields. When represented as a flattened set, child field definitions appear as siblings sequentially after the parent field definition.
Use the properties and methods of TFieldDefs to:
Access a specific field definition.
Add or delete field definitions from the list (when creating new tables).
Find out how many fields are defined.
Copy a set of field definitions to another dataset.