db.getCollection("vocsdatas").aggregate([
{$match:{devname:{$regex:'Côté nord du parc (sous-station Lvyi)'}}},
{$group:{_id : "$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 :{$max :"$fengsu"},fengxiang :{$max:"$fengxiang"},ben :{$max:"$ben"},jiaben :{$max:"$jiaben"}, yiben :{$max:"$yiben"},yiererjiaben:{$max:"$yiererjiaben"},jianduierjiaben:{$max:"$jianduierjiaben"},jiawan:{$max:"$jiawan"},feijiawanzongting : { $max:"$feijiawanzongting"},so2:{$max:"$so2"},h2s:{$max:"$h2s"}}},
{$project:{_id:0,sendtime:" $ _id", nom dev : 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}},
{$sort:{sendtime:-1}},
{$ sauter :20},
{$limit:10}
]
)