Different result same query on FB5.0.2.1583 vs FB2.5.6.26967

[OlegMatveevFB]

SELECT prc.ID_NEW, t.ID
FROM P12 prc
LEFT JOIN T1 t ON t.id=prc.ID_NEW

FB5.0.2.1583
ID_NEW ID
2 < null >

FB2.5.6.26967
ID_NEW ID
2 2

Metadata:

CREATE TABLE T1 (ID INTEGER);

CREATE SEQUENCE GEN_T1_ID;

SET TERM ^ ;

CREATE TRIGGER T1_Bi FOR T1
ACTIVE BEFORE INSERT POSITION 0
AS
BEGIN
IF (NEW.Id IS NULL) THEN
NEW.Id = GEN_ID(Gen_T1_Id,1);
END^

CREATE PROCEDURE P12
RETURNS (ID_NEW INTEGER)
AS
BEGIN
ID_NEW = GEN_ID(Gen_T1_Id, 1);
INSERT INTO T1 (id) VALUES (:ID_NEW);
SUSPEND;
END^

SET TERM ; ^

COMMIT;

[aafemt]

As designed: Firebird 5 has cursor stability so query cannot see own changes.