Hi Bin,
As I mentioned before, please try to query Purchase Order in Repository Explorer before writing codes.
I am also checking the data.
Can you please share your codes by the way?
Update - Cannot navigate ItemProductTaxDetails Association using Query result in Repository Explorer . Studio shuts down when navigated.
Anyway, this path should include the rate.
PurchaseOrder.Item.TaxCalculationItem.ItemProductTaxDetails.ProductTax.Rate
Best Regards,
Fred