CURRYEAR:=$(shell date +%Y)
LASTYEAR:=$(shell expr $(CURRYEAR) - 1)
YEARBEFORE:=$(shell expr $(CURRYEAR) - 2)

assignmentsheet1.pdf	: assignmentsheet1.tex problems.dbtex
			pdflatex assignmentsheet1

problems.dbtex	: mth101.dbtex
		datatooltk --in mth101.dbtex \
		--merge Label mth101-years.dbtex \
		--shuffle \
		--filter-and \
		--filter Year ne $(LASTYEAR) \
		--filter Year ne $(YEARBEFORE) \
		--truncate 5 \
		--output problems.dbtex

update		: 
		datatooltk --in mth101-years.dbtex \
		--filter Year eq $(LASTYEAR) \
		--filter Year eq $(YEARBEFORE) \
		--output mth101-years.dbtex