yes, phases that you are talking are very simple and straigth forward...
but in this case, you miss one point; when you create a summary view according to + and -
to find the final stock level, you could not say this 100 stock comes from which stock entry.
to do that you should create a loop for each item for each day.. since the data volume that i am dealing is so huge, i need to find some other way to handle this case.
i attach a simple QV document for your reference to make it clear for you.
In my sample data set, first 2 entries are + and they are 100, 25. after those entries there is a sales which is 25 and stock level drops to 100..
if i do your suggestion; my final stock level will seen as 100 and my first stock level will seen 100 and it says, it is related with that.. but according to FIFO (First In First Out), my 25 sales should be substract from my first inventory entry which 100..