Null

function Null: Boolean

Example

procedure ScriptEvent(var Value: variant);
begin
  if Field.Null then
    Value := 'No database value'
  else
    Value := Field.Value;
end;

Usage

Returns the live field's exact database-null state as a method.

Additional Technical Info

Null is an exact method alias for the inherited read-only IsNull property.

It returns true only when the current field has no assigned database value. Empty text, whitespace text, numeric zero, Boolean false and date/time zero are present values and return false.

This method is unrelated to the Pascal/Variant Null value constructor except for its name. In an expression, Field.Null is a Boolean test; assigning Value := Null uses the Variant null intrinsic.

The state follows the current dataset record. The test has no write/post/navigation side effect and is constant-time for a normal field. Use IsNullEmpty or IsNullZero only when their wider sentinel rules are intended.

External references

• Embarcadero DocWiki: TField.IsNull documents the exact property returned.
• Free Pascal: TField.IsNull documents compatible field-null behavior.

Created 2026-07-15