I have a table that forecasts our Sales for the upcoming year. It contains the following columns: Year (DATE), Company (VARCHAR), Product (VARCHAR), ProductType (VARCHAR), LastYearsSales (INT), ForecastSales (INT).
I would like to increase the ForecastSales for particular ProductTypes in the table. So for example for all the LEISURE products I would like to increase the forecasted sales figures by 1000. I don't want to add a 1000 to each LEISURE product but share the 1000 over all of the LEISURE products ie if there were 10 LEISURE products in the table then increase each of their sales by 100 (1000/10).
Thanks in advance.