queries.txt

//MGDB1
db.delegates.find()*

* every find() could be followed with .pretty() so that the search results will be displayed more readable.

//MGDB2
db.delegates.count()

//MGDB3
db.conferences.find({},{_id:1})

//MGDB4
db.conferences.find({co_located_with:"ICSE'41"})

//MGDB5
db.conferences.find({"duration.end" : {$gt: "2019-04-15"}})

//MGDB6
db.delegates.find({},{name:1,country:1,_id=0})

//MGDB7
db.conferences.find( {tracks : {$exists:true}, $where:'this.tracks.length>1'})

//MGDB8
db.conferences.find({name: {$regex: 'ICSE'}}, {edition: true, _id:false})

//MGDB9
db.delegates.update({name : "Sonia Haiduc"}, {$set : { "country" : "Australia"}})

//MGDB10
db.delegates.update({name: "Michael Whalen"},{$set: {"attends": [{"conference":"ICSE'41","registered":"2019-02-01"}]}})

//MGDB11
db.delegates.count({country: {$regex : 'USA'}})

//MGDB12
db.conferences.aggregate([{$lookup: {from: "delegates",localField: "general_chair", foreignField: "name", as: "conferences"}},   {$match: {"conferences.country" :{$regex: 'USA'}}}, {$project: { "name": true, _id:false}}])