mongoDB中文网

db.college.find().length();

db.college.find({name:"HTML5"});

db.college.update({name:"HTML5"},{$set:{intro:"打通全栈任督二麦"}});

db.college.find();

db.college.update({name:"K12"},{$set:{name:"大数据"}});

db.college.update({name:"PHP"},{$unset: {intro:1}});

db.college.update({name:"HTML5"},{$set:{classes:{base:["h5+c3","js"],core:["三大框架","nodejs"]}}});

db.college.find({"classes.core":"三大框架"});

db.college.update({name:"HTML5"}, {$push: {"classes.core": "微信小程序"}});

db.college.update({name:"HTML5"}, {$addToSet: {"classes.core": "公众号开发"}});

db.college.find();

var arr = [];
for (var i=0; i<10000; i++) {
    arr.push({counter:i});
}
db.demos.insert(arr);
db.demos.find();

db.demos.find({counter: {$lt:666}});
db.demos.find({counter: {$gt:666}});

db.demos.find({counter: {$lt:666,$gt:66}});

db.demos.find({counter: {$lte:10}});
db.demos.find().limit(10);

分页

db.demos.find().skip(10).limit(10);

或

db.daodanlian.find({$or:[{wages: {$lt:10000}}, {wages: {$gt:20000}}]});
//符合条件添加
db.daodanlian.updateMany({wages:{$lte:1000}}, {$inc: {wages:1000}})

1、集合之间的关系

1. one to one
2. one to many
3. many to many

db.students.remove({"_id" : ObjectId("5cf10ec40d488ef20fc2e9be")});

2、排序和索引

1. 排序

db.teacher.find().sort({wages:1}) // 1升序  -1降序
db.teacher.find().sort({wages:1, _id: -1})

2.索引

db.teacher.find({}, {name:1, _id:0,wages:1}); //1显示 0不显示