SAP Business One query that shows the best sold product by group

 SELECT T0.GroupCode, T1.ItemCode, T1.ItemName, SUM(T1.Quantity) AS 'Total Sales'

FROM OCRG T0 INNER JOIN OITM T1 ON T0.GroupCode = T1.ItmsGrpCod INNER JOIN INV1 T2 ON T1.ItemCode = T2.ItemCode GROUP BY T0.GroupCode, T1.ItemCode, T1.ItemName ORDER BY T0.GroupCode, SUM(T1.Quantity) DESC