SELECT
DM.ID_MAG AS NR_MAG,
EXTRACT(YEAR FROM DM.DATA_DOC) AS ROK, EXTRACT(MONTH FROM DM.DATA_DOC) AS MIESIAC ,
COALESCE((SELECT SUM(DMP.WART_NETT)
FROM
DOC_MAG DMP
INNER JOIN MAG_TYP_DOC MTD2 ON DMP.TYP_DOC=MTD2.ID
WHERE
(DMP.ID_MAG=DM.ID_MAG)
AND (MTD2.TYP=1)
AND (DMP.STATUS=1)
/* here are problem */
AND (DMP.DATA_DOC>=
CAST(EXTRACT(YEAR FROM DM.DATA_DOC) || '-' || EXTRACT(MONTH FROM DM.DATA_DOC) || '-01' AS DATE)
AND
DMP.DATA_DOC<CAST(EXTRACT(YEAR FROM DATEADD(1 MONTH TO DM.DATA_DOC)) || '-' || EXTRACT(MONTH FROM DATEADD(1 MONTH TO DM.DATA_DOC)) || '-01' AS DATE)
)
/* end of problem */
AND ( ((EXTRACT(YEAR FROM DMP.DATA_DOC)=EXTRACT(YEAR FROM DM.DATA_DOC)) AND (EXTRACT(MONTH FROM DMP.DATA_DOC)=EXTRACT(MONTH FROM DM.DATA_DOC))) )
),0 ) AS PRZYCH_MIES
FROM
DOC_MAG DM
WHERE
(DM.ID_MAG=23)
GROUP BY DM.ID_MAG, EXTRACT(YEAR FROM DM.DATA_DOC), EXTRACT(MONTH FROM DM.DATA_DOC)
ORDER BY DM.ID_MAG, 2 DESC, 3 DESC

--------------------------------------------
i got error

SQL Message : -104
Invalid token

Engine Code : 335544569
Engine Message :
Dynamic SQL Error
SQL error code = -104
Invalid expression in the select list (not contained in either an aggregate function or the GROUP BY clause)

---------------------------------------------
is this FB problem or i doing some wrong??

i try tis "problematic" expression against simple select and work ok - what is wrong?
SELECT
CAST(EXTRACT(YEAR FROM DATEADD(1 MONTH TO DM.DATA_DOC)) || '-' || EXTRACT(MONTH FROM DATEADD(1 MONTH TO DM.DATA_DOC)) || '-01' AS DATE)
FROM
DOC_MAG DM

Karol Bieniaszewski