SQL is not the proper tool to do sequential operations such as cumulative sums. Use a datastep instead, it will be simpler and much faster. data have; input ID  Year    Month   Value; datalines; 12345   2013    5   -94.32 12345   2013    6   19.82   12345   2013    7   55.49   12345   2013    8   28.73   12345   2013    9   -24.6   12345   2013    10  -36.4 ; proc sort data=have; by id year month; run; data want; set have; by id; if first.id or sum>0 then sum=0; sum + value; run; proc print data=want noobs; run; PG ... View more