declare
  dup_val_on_index  exception;
  except_02275  exception;

  pragma exception_init (dup_val_on_index  , -01430);
  pragma exception_init (except_02275  , -02275);
begin
  execute immediate 'ALTER TABLE LOG_CONFERENCIA ADD CONSTRAINT FK_LOGCONFERENCIA_TIPOINFOR FOREIGN KEY (TIPOINFORMATIVOCOMISSAO_ID) REFERENCES TIPO_INFORMATIVO (TIPOINFORMATIVO_ID)'; 

  exception 
    when dup_val_on_index  then null;
    when except_02275  then null;
end;