Ok, I have changed into this (directly in database)
SELECT plb_Umowa.up_IdPracownika, plb_Wyplata.wyp_StatGodzPrzepr, YEAR(plb_ListaPlac.lp_Miesiac), MONTH(plb_ListaPlac.lp_Miesiac), SUM(plb_Wyplata.wyp_ObciazeniePracodawcy) as sumaWypl
FROM plb_Wyplata
INNER JOIN plb_Umowa ON plb_Wyplata.wyp_IdUmowy = plb_Umowa.up_Id
INNER JOIN plb_ListaPlac ON plb_Wyplata.wyp_IdListyPlac = plb_ListaPlac.lp_Id
WHERE (YEAR(plb_ListaPlac.lp_Miesiac) LIKE '2020') AND (MONTH(plb_ListaPlac.lp_Miesiac) LIKE '7')
GROUP BY plb_Umowa.up_IdPracownika, plb_Wyplata.wyp_StatGodzPrzepr, YEAR(plb_ListaPlac.lp_Miesiac), MONTH(plb_ListaPlac.lp_Miesiac)
and it gives table, however SUM still doesn't work
1 8640 2020 7 8538,67
1 11040 2020 7 1707,68
2 8640 2020 7 6213,97
2 11040 2020 7 835,04
3 8640 2020 7 8979,44
3 11040 2020 7 1365,54
4 8640 2020 7 7174,34
4 11040 2020 7 1367,09
6 4320 2020 7 5784,02
8 8640 2020 7 9359,85
8 11040 2020 7 1534,02
9 1000 2020 7 698,11
10 8640 2020 7 7940,45
10 11040 2020 7 1707,68
11 8640 2020 7 8865,41
11 11040 2020 7 1707,66
12 8640 2020 7 9094,79
12 11040 2020 7 1367,07
It shoud be grouped by first column and las amount summed.
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