I asked a question yesterday, which has been answered but I have an additional question that takes it that step further. I will repeat the first question then move on to my actual question:
Say I have a straight table with 4 fields:
I would like to add a 5th field which is an aggregate function but only grouped by the year, i.e. I want to add quanity_year which is the sum of quantity for the year. Can I do this using an expression?
example data below (for illustrative purposes):
year quarter month quantity year_quanity
2011 1 1 3 14
2011 2 . 5 14
2011 3 . 6 14
2012 1 . 8
ANSWER: defining year_quantity as an expression defined as =sum(TOTAL <year> quantity). This works fine and achieve what I required as long as the year field is included in the straigh table.
Say I have the same data (as in table above) but this time I want to have a concatination of year and month as one field, then the sum of quantity. In other words, I want to remove the fields year, quarter, month and only have 3 fields, as below.
year_month quantity year_quanity
2011 1 3 14
2011 . 5 14
2011 . 6 14
2012 . 8
This however does not work as now the field year is not included in the straight table and the year_quantity expression stops working. The expression ends up giving me a total quanity over the whole dataset and does not factor in year at all.
Any ideas on how I can get the sum of quantity grouped by year but without actually including the year in the straight table? I know I could do this as a preporcessing step (say via sql) or via the load script but I was hoping to do this via an expression.