Hi there, I have 2 problems to solve:
1-
I want to sort a table of calls which includes calling destinations, type of
phone called and sum the cost of each call.
eg: here are the three columns
UK mobile 0.5c
US fixed 0.5c
UK mobile 0.4c
US mobile 0.3c
US fixed 0.1c
UK mobile 0.5c
France mobile 10c
Germany mobile 25c

I would like to return a separate table of rows for each destination and
call type with totals for the cost of the calls and sorted by most costliest:
Germany mobile 25c
France mobile 10c
UK mobile 1.4c
US fixed 0.6
US mobile 0.3

2-
some of the destinations have a special rate, but you can use only for one
destination. I would like to take the costliest destination used that has a
special rate and apply that rate as an alternative to the standard rate in a
separate column.
So, if we say that most money spent on destination is Germany but it doesn't
have a special rate, second most money spent on destination is France mobile
and it does have a special rate, then in a separate alternative price column,
use that special rate instead of standard rate. For all other destinations,
default to the standard rate.
Thanks!!