CREATE TABLE INF$ABONENT$BT (
    ID                    D_KEY NOT NULL /* D_KEY = INTEGER */,
    ID_ABONENT            D_KEY NOT NULL /* D_KEY = INTEGER */,
    ID_SERVICE            D_KEY NOT NULL /* D_KEY = INTEGER */,
    ID_PERIOD             D_KEY NOT NULL /* D_KEY = INTEGER */)

ALTER TABLE INF$ABONENT$BT ADD CONSTRAINT UNQ_INF$ABONENT$BT UNIQUE (ID_ABONENT, ID_SERVICE, ID_PERIOD);

SELECT MIN(BT.ID_PERIOD) FROM INF$ABONENT$BT BT WHERE (BT.ID_ABONENT = :ID_ABONENT) AND (BT.ID_SERVICE = :ID_SERVICE)

PLAN (BT ORDER FK_INF$ABONENT$BT_PERIOD INDEX (UNQ_INF$ABONENT$BT))

SELECT MIN(BT.ID_PERIOD + 0) FROM INF$ABONENT$BT BT WHERE (BT.ID_ABONENT = :ID_ABONENT) AND (BT.ID_SERVICE = :ID_SERVICE)

PLAN (BT INDEX (UNQ_INF$ABONENT$BT))

PLAN (BT ORDER UNQ_INF$ABONENT$BT)