好吧，我正在尝试将此sql查询转换为mapreduceselecto_orderpriority,count(*)asorder_countfromorderswhereo_orderdate>=date'1993-07-01'ando_orderdate我尝试了以下mapreduce函数db.runCommand({mapreduce:"orders",query:{o_orderdate:{'$gte':newDate("July01,1993")},o_orderdate:{'$lt':newDate("Oct01,1993")}},map:functionMap(){for(v