I have a table of Orders and each Order has multiple Task and a Order_Total currency field.

each Task is assigned to one Staff.

How can i create a chart like the following

X-axis: different Staff

Y-axis: the Order_Total of all Orders of the Staff on x-axis.

My difficulty is, when I create a chart base on Task, i can't reference the Order's Order_Total field.

If i create a chart based on Order, i can't set the x-axis to Staff.