bar结合rowNo可以实现，示例如下，每2行一组计算qty之和：
t = table(1..10 as id, rand(100,10) as qty)
select sum(qty) from t group by bar(rowNo(id),2)
bar结合rowNo可以实现，示例如下，每2行一组计算qty之和：
t = table(1..10 as id, rand(100,10) as qty)
select sum(qty) from t group by bar(rowNo(id),2)