NotNullZero

function NotNullZero: Boolean

Example

procedure ScriptEvent(var Value: variant);
begin
  if Field.NotNullZero then
    Value := Field.Value
  else
    Value := 'Missing or zero';
end;

Usage

NotNullZero returns the exact negation of Velox's type-dependent null-or-zero sentinel predicate.

Additional Technical Info

NotNullZero returns not IsNullZero and therefore inherits that method's type-dependent rules.

• For Velox numeric/date types it is false for Variant Null/Empty/Clear and values equal to zero.
• For every other type it is false when Trim(VarToStr(Value)) is empty.

Consequently Boolean true is normally true and Boolean false is false; a string '0' is true; numeric zero and Delphi date/time zero are false. This is not the same as database non-null.

The method reads the current field once through the underlying IsNullZero call. Variant conversion/comparison can raise for unsupported values. It does not write or navigate.

External references

• Embarcadero DocWiki: VarToStr documents the nonnumeric conversion used beneath this predicate.
• Embarcadero DocWiki: TField.IsNull distinguishes database null from the wider Velox sentinel rule.

Created 2026-07-15