Hey.. I have a database about car's fuel and anyway..i want to create a query that calculates the km in a month, the liter_quantity of fuel in a month a total_norme=liter_quantity/km_in_month.
For liter quantity, i make a sum of that field, for a specified month.
for km_in_month, i make Km_end_Month - Km_Begin_Month.
but when i want to find the total_norme, it doesn't work...can you help me please, what should i put in the Norme field as expression ?