Problem with multiple table updating query

[fekrinejat]

I have got two tables:

Person(ID,Name,LastBuy,Price_Sum)
Sales(ID,Person_ID,Date,Price)



There is a relationship between Person.ID and Sales.Person_ID. Now I need to write a query in order to calculate sum of Price field for every person and update result into the Person.Price_Sum field, Then just find the latest buy of everyone through Sales.Date and update into the Person.Lastbuy.
That sounds complex, I would be really grateful if someone helps me.

[June7]

Why save calculated data? Saving calculated data, especially aggregate calcs, is usually a bad idea. Since it must be calculated in order to save it, why bother with the extra and complicated step - just run the calculation whenever needed.

[fekrinejat]

Thanks, but what about having calculated fields in Person table which going to be changed whenever data changes on Sales Table ?
Would you guide me by a real query code for better understanding ?

[June7]

The sum calculation and determining latest date are easy and basic Access functionality. Use Query designer to join the two tables. Use that query as the basis for further data manipulation. Can either do a GROUP BY (aggregate) query with Sum of Price field and Max of Date field or build a report using Grouping & Sorting with aggregate calcs. Report will allow display of detail records as well as summary calcs in group header/footer.

GTW, advise not to use reserved words as names. Date is a reserved word.