uniquearray(maparray(range(todate($开始年月+"-01"),todate($结束年月+"-01")),left(item,7)))
=
uniquearray(maparray(range(todate(today()),todate(monthdelta(today(),3))),left(item,7)))
============
uniquearray(maparray(range(todate(today()),todate(monthdelta(today(),3))),format(item,"yyyyMM")))