MongoDB里面怎么 查最值

Question

MongoDB里面怎么 查最值

Answer 1

mongodb中有聚合函数，可以使用聚合函数查询最值。案例代码：//计算时间编号exports.maxSJBH = function ( callback) {var proxy = new EventProxy();PerMYDFXMongooseModel.aggregate([{$group: {_id: null,maxsjbh: {$max: "$sjbh"}}},{$project: {_id: 0,maxsjbh: "$maxsjbh"}}], proxy.done('models'));proxy.all('models', function (models) {callback(null, models);});} 

Answer 2

1db.collectionName.find({},{"_id":1}).sort({"_id":-1}).limit(1);