前面用over函数的AllPrevious选项实现了累计值的计算，效果如下：
这张图表现的是“单调上升”的销售额，并没有按年分组。如果要按年分组，就需要联合使用Intersect选项及Parent选项了。
各季度销售额的直方图如下所示：
问题：如何展现出各时间段内（年、季度、月、星期、天、小时、分、秒）以其上一层级为分组单位的累计销售额？
解决方案：单击图标左侧Y轴销售额，编辑公式为“Sum([Sales Total]) Over(Intersect(AllPrevious([Axis.X]),Parent([Axis.X])))”，即可实现该要求。
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以下内容摘自官网文档：
The OVER functions are used to determine how data should besliced, for example, relative to time periods. For more information, see OVERin Custom Expressions and Advanced Custom Expressions.
Option: Intersect
Returns the intersected rows from nodes in differenthierarchies. See also AllPrevious and All.
Example:
Intersect(Parent([Axis.X]), All([Axis.Color]),Parent([Axis.Rows]), ...)
以下内容摘自培训资料：
The Intersect() methodwill find and return only the overlapping data found by two or more other nodenavigation functions.
A good example of using the Intersect()method is to show cumulatively summing revenue per year.