Challenge

Many applications that use a master/detail format will need to display a total from the detail records on a summary page for the master records.  For example when viewing a list of sales invoices it is usual to show the invoice totals - this will normally be the summation of individual invoice line amounts.

In our project, so far, we have a master/detail page that lists cities by countries with the population of each city held on the city record.  The challenge is to change the Countries page to display the total population of the cities by country.

When complete, the revised Countries page should look similar to this:

A YouTube video of a possible solution will be posted in due course, with a link here.