In one lookup table I have 4 tasks listed. Every task can occur or not
during a day in one, more or all timeshifts.
I have 3 timeshifts : morning - afternoon - evening.

morning | afternoon | evening
januari task1 | task1 | task2
januari task1 | no task | task4
januari task3 | task2 | task3

at the end I wan't a query with the total hours spend on a task for a
month.

januari | task1 | totals (morning afternoon evening)
januari | task2 | totals ...
januari | task3 | totals ...
januari | task4 | totals ...

now I have already a query which start form the tasks in the morning,
if there is a tasknumber he takes that. The problem is, when there is
not a tasknumber in the morning for a certain month and there is one
in the afternoon or the evening, my query is missing this data for the
afternoon or evening.
To avoid incompleet data, how must I say for every month take all the
task (here for the moment there are 4) even is this task is not
mentioned in the morning. In other words, he should always takes all
the tasks mentioned in the lookup table and repeat them for every
month (month based on the day - every day I put in tasks). The
timeshifts where he could not find a task he simply put a zero.