A workshop about MongoDB. Created for University of West Bohemia.
Server
# linux
mongod --dbpath /data/db
# windows
mongod.exe --dbpath D:\Database\MongoDB\data
Client
# linux
mongo
# windows
mongo.exe
use friendfaceSyntax: db.<collection-name>.insert(<document>)
// INSERT INTO users (username, name, sex, age) VALUES ('jon.doe', 'Jon Doe', 'male', 34);
db.users.insert({"username":"jon.doe","name":"Jon Doe","sex":"male","age":34);
db.users.insert({"username":"elison_heart","name":"Elison Heart","sex":"female","age":18);
// it's not problem to change schema - because there's not schema
db.users.insert({"username":"fanda","name":"František Vopršálek","sex":"Příležitostně", "hobbies":["NoSQL","BigData","pivo"]);
// it's possible to nest documents
db.users.insert({"username":"jim.kirk","name":"James T. Kirk","setup":{"subscribe":true,"email":"[email protected]"}});MongoDB automatically creates field _id (equivalent to auto-increment in MySQL)
Syntax: db.<collection-name>.find([<query-document>],[<select-document>])
// SELECT * FROM users;
db.users.find();
// SELECT * FROM users WHERE username = 'fanda';
db.users.find({"username":"fanda"});
// SELECT * FROM users WHERE age < 20;
db.users.find({"age":{"$lt": 20}});
// SELECT username FROM users WHERE sex IN ('male','female');
db.users.find({"sex":{"$in":["male","female"]}});
// SELECT * FROM users LIMIT 1;
db.users.find().limit(1);
// SELECT * FROM users ORDER BY age DESC,name;
db.users.find().sort({"age":-1,"name":1});Syntax: db.<collection-name>.update(<query-document>,<set-document>);
// UPDATE users SET age = 35 WHERE username = 'jon.doe';
db.users.update({"username":"jon.doe"},{"$set":{"age":35}});Syntax: db.<collection-name>.remove(<query-document>);
// DELETE FROM users WHERE age >= 50;
db.users.remove({"age":{"$gte":50}});# linux
mongoimport --db friendface --collection users < users.json
# windows
mongoimport.exe /d friendface /c users /file users.json
Syntax: db.<collection-name>.ensureIndex(<index-document>);
// simple index
db.users.ensureIndex({"username":1});
// compound index
db.users.ensureIndex({"username":1, age: 1});
// count average age by gender
db.users.aggregate([
{"$group":{"_id":"$sex","average":{"$avg":"$age"}}}
]);
// map name (first name and last name separately) as key, value always 1
var map = function () {
this.name.split(' ').forEach(function (name) {
emit(name, 1);
});
};
// sum up all given values
var reduce = function (key, values) {
return Array.sum(values);
}
db.users.mapReduce(map, reduce, {"out":"users_names"});
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