Создание UDF для InterBase

library nikelutils

uses SysUtils, Classes;

function MaxInt(var Int1, Int2: Integer): Integer;
  far cdecl export;
begin
  if (Int1 > Int2) then
    Result := Int1
  else
    Result := Int2;
end;

function MinInt(var Int1, Int2: Integer): Integer;
  far cdecl export;
begin
  if (Int1 < Int2) then
    Result := Int1
  else
    Result := Int2;
end;

exports
  MaxInt;
MinInt;

begin
end.

А это пишим в базе:

DECLARE EXTERNAL FUNCTION MAXINT INTEGER, INTEGER
RETURNS INTEGER BY VALUE
ENTRY_POINT "MaxInt" MODULE_NAME "nikelutils.dll";

DECLARE EXTERNAL FUNCTION MININT INTEGER, INTEGER
RETURNS INTEGER BY VALUE
ENTRY_POINT "MinInt" MODULE_NAME "nikelutils.dll";
 

Взято с https://delphiworld.narod.ru