db.getCollection("vocsdatas").aggregate([

{$match:{devname:{$regex:'Sebelah utara taman (Lvyi Substation)'}}},

{$group:{_id : "$sendtime",devname:{$max:"$devname"},qyname:{$max:"$qyname"},no:{$max:"$no"},no2:{$max:"$ no2 "},nox:{$max:"$nox"},nh3:{$max:"$nh3"},wendu:{$max:"$wendu"},shidu:{$max:"$shidu" } ,fengsu:{$maks:"$fengsu"},fengxiang:{$maks:"$fengxiang"},ben:{$maks:"$ben"},jiaben:{$maks:"$jiaben"}, yiben :{$maks:"$yiben"},yiererjiaben:{$maks:"$yiererjiaben"},jianduierjiaben:{$maks:"$jianduierjiaben"},jiawan:{$maks:"$jiawan"},feijiawanzongting: { $maks:"$feijiawanzongting"},so2:{$maks:"$so2"},h2s:{$maks:"$h2s"}}},

{$projek:{_id:0,sendtime:" $ _id",devname:1,qyname:1,no:1,no2:1,nox:1,nh3:1,wendu:1,shidu:1,fengsu:1,fengxiang:1,ben:1,jiaben: 1 ,yiben:1,yiererjiaben:1,jianduierjiaben:1,jiawan:1,feijiawanzongting:1,so2:1,h2s:1}},

{$sort:{sendtime:-1}},

{$ langkau :20},

{$limit:10}

]

)