MONGODB高级操作

db.MobileArea.count()

db.MobileArea.distinct("Mobile")

db.MobileArea.group({
"key":{"Mobile":true},
"initial":{"Mobile":[]},
"$reduce":function(counts,mob){
mob.Mobile.push(counts.Mobile);
},
"finalize":function(out){
out.count=out.Mobile.length;
},
"condition":{"Province":"山东"}
})

db.MobileArea.find().explain()

db.MobileArea.ensureIndex({"Mobile":-1})

db.MobileArea.ensureIndex({"Mobile":-1},{"unique":true})

db.MobileArea.ensureIndex({"Province":-1},{"City":-1})

db.MobileArea.getIndexes()

db.MobileArea.dropIndex("Province_-1")