function FieldByName(const FieldName: String): TField;
Call FieldByName to retrieve field information for a field when only its name is known.
FieldName is the name of an existing field. FieldByName returns the TField
component for the specified field. If the specified field does not exist, FieldByName raises an
FieldName can be the name of a simple field, the name of a subfield of an object field
that has been qualified by the parent field name, or the name of an aggregated field. Because of this
flexibility, it is often preferable to use FieldByName rather than the Fields property or
the AggFields property.
An application can directly access specific properties and methods of the field returned by
FieldByName. For example, the following statement determines if a specified field is a calculated
field or not:
if Customers.FieldByName('FullName').Calculated then
MessageDlg(Format('%s is a calculated field. ',
FieldByName is especially useful at design time for developers who are creating database
applications, but who do not have access to the underlying table and therefore cannot use persistent
To retrieve or set the value for a specific field, call the default dataset method
FieldValues instead of FieldByName.