I want to analyze the sales of 20 hotel during the las 30 months so I made a table with three fields (month, year, hotel) resulting 600 rows, obviously.
Then I made a join of the sales table (month, year, hotel, salesamount) but I 'loose' rows, because not all the hotels were open in a specific month so they have no row for that month-year-hotel.
If there is no sales value for a specific month-year-hotel I would need a '0' as saleamount instead of a dissapeared row.
