SET TERM ^ ;
 
CREATE OR ALTER PROCEDURE UTIL_IS_VALID_CPF (
    CPF CHAR(11) CHARACTER SET WIN1252)
RETURNS (
    VALIDO SMALLINT)
AS
DECLARE variable SOMA INTEGER;
DECLARE variable RESTO SMALLINT;
DECLARE variable CONT SMALLINT;
BEGIN
  -- código da comunidade show delphi, adaptado por Giovani Da Cruz
 
  /* DIGITOS IDENTICOS */
  IF (
  (CHARACTER_LENGTH(CPF) <> 11) OR
  (CPF = '00000000000') OR (CPF = '11111111111') OR
  (CPF = '22222222222') OR (CPF = '33333333333') OR (CPF = '44444444444')OR
  (CPF = '55555555555') OR (CPF = '66666666666') OR (CPF = '77777777777')OR
  (CPF = '88888888888') OR (CPF = '99999999999')
  ) THEN
  BEGIN
    VALIDO = 0;
 
    SUSPEND;
    Exit;
  END
 
  /* INICIALIZA VARIÁVEIS */
  CONT=1;
  SOMA=0;
  RESTO=0;
 
  /* SOMA OS DÍGITOS MULTIPLICADOS E CALCULA O RESTO */
  WHILE (CONT<=9) DO
  BEGIN
    SOMA = SOMA + CAST( SUBSTRING(CPF FROM :CONT FOR 1) AS SMALLINT) * (11 - :CONT);
    CONT = CONT + 1;
  END
  RESTO=MOD(SOMA,11);
 
  /* TRATA O CASO DE RESTO INFERIOR A 2 */
  IF ( (RESTO < 2) AND (SUBSTRING(CPF FROM 10 FOR 1) <> '0') )THEN
  BEGIN
    VALIDO = 0;
  END
  ELSE
  BEGIN
    /*VERIFICA SE O PRIMEIRO DIGITO CONFERE*/
    IF (11-:RESTO<>CAST(SUBSTRING(CPF FROM 10 FOR 1) AS INTEGER)) THEN
    BEGIN
      VALIDO=0;
    END
    ELSE
    BEGIN
      CONT=1;
      SOMA=0;
 
      /*MULTIPLICA, SOMA E CALCULA O RESTO*/
      WHILE (CONT<=10) DO
      BEGIN
        SOMA = SOMA + CAST(SUBSTRING(CPF FROM :CONT FOR 1) AS SMALLINT) * (12-:CONT);
        CONT = CONT + 1;
      END
      RESTO = MOD(:SOMA,11);
 
      /*VERIFICA O SEGUNDO DÍGITO*/
      IF ((RESTO < 2) AND (SUBSTRING(CPF FROM 11 FOR 1) <> '0')) THEN
      BEGIN
        VALIDO=0;
      END
      ELSE
      BEGIN
        IF (11 - :RESTO <> CAST(SUBSTRING(CPF FROM 11 FOR 1) AS INTEGER)) THEN
        BEGIN
          VALIDO = 0;
        END
        ELSE
        BEGIN
          VALIDO = 1;
        END
      END
    END
  END
 
  SUSPEND;
END
^
 
SET TERM ; ^

SELECT
 
-- válido gerado pelo gerador de cpf do show delphi
(SELECT y.valido FROM util_is_valid_cpf('47570414039') y),
 
-- inválido
(SELECT y.valido FROM util_is_valid_cpf('00000000000') y),
 
-- in
(SELECT y.valido FROM util_is_valid_cpf('01294580043') y)
 
FROM rdb$database