Mongodb basic exercises

10 practice 1

// Access to database 
user my_test

// Insert a document 
db.user.insert({
	username:"subway"
});

// Query the document 
db.user.find();

// To the database user Insert a document into the collection 
db.user.insert({
	username:"zhengji"
});

// Inquire about user Document for collection 
db.user.find();

// Count the number of collection documents 
db.user.find().count();

// Add... To the document address attribute , The value is huaguoshan
db.users.insert({username:"sunwukong",{$set:{address:"huaguoshan"}}});

// Document replacement 
db.users.resplaceOne({username:"zhubajie"},{username="tangsen"});

// Delete document properties 
db.user.update({username:"sunwukong"},{$unset:{address:1}});

// Add a... To the document hobby by {} Properties of 
// The attribute value of a document can also be a document , At this time, this document is ” Embedded documents “
db.users.update({username:"sunwukong",{$set:{...}}})

//mongodb Support query directly through embedded document properties 
// If you want to query documents through embedded documents , Attribute names must be quoted 
db.users.find({'hobby.movie':"hero"});

// towards tangsen Add a new movie to Intersteller
//$push Used to add new elements to the array 
//$addToSet  Add a new element to the array , But don't repeat 
db.users.update({username:"tangsen"},{$push:{"hobby.movies":"Installer"}});

// Delete likes beijing  Users of 
db.users.remove({"hobby.cities":"beijing"});

// Delete user aggregate 
db.users.remove({});
db.users.drop();

// towards numbers Insert 2000 Data 
for(var i=1;i<=20000;i++){
	db.numbers.insert({num:i});
}

// Performance optimization 
var arr=[];
for(var i=1;i<=20000;i++){
	arr.push({num:i});
}
db.numbers.insert(arr);

11 practice 2

Inquire about

// Inquire about numbers in num by 500 Documents 
db.numbers.find({num:500})

// Inquire about numbers in num>500 Documents 
db.numbers.find({num:{$gt:500}});

// Inquire about num Less than 30 Documents 
db.numbers.find({num:{$lt:30}});

// The query is greater than 40 Less than 50
db.numbers.find({num:{$gt:40,$lt:50}});

// check numbers Before the assembly 10 Data 
db.numbers.find({num:{$lte:10}});
//limit Set the upper limit of display data    benefits ： You will never execute queries without conditions during development 

db.numbers.find().limit(10); 

// Check before 11-20 strip 
//skip Used to skip a certain amount of data before 
//skip(( Page number -1)* Number of entries per page )
db.numbers.find().skip(10).limit(10);

//mongo Automatic adjustment  skip and limit Location   The front and rear positions have no effect 

13 practice 3

// Import collection into database 
// Select the... To import collection


// Query salary less than 2000 The employees' 
db.emp.find({sal:{$lt:2000}});

// Check salary at 1000-2000 staff 
db.emp.find({sal:{$gt:1000,$lt:2000}});

// Check that the salary is less than 1000 Or greater than 2500 staff 
//  Wrong way   db.emp.find({sal:{$lt:1000,$gt:2500}});
db.emp.find({$or:[{sal:{$lt:10000},${gt:2500}}]});

// Check all employees in the finance department 
var depno=db.dept.findOne({dname:" Finance Department "}).deptno;
db.emp.find({depno:depno});

// Query all mgr by 7698 All employees 
db.emp.find({mgr:7698});

// Wages below 1000 Employee salary plus 400
db.emp.updateMany({sal:{$lte:1000}},{$inc:{sal:400}});