Mongo DB short Commands on how to go about the basics in CRUD operations

gistfile1.js

// mongoDB Shell Commands... 

// show dbs - show databases. 
// use mycustomDatabase - create database and switch 
// db - show me the current database being used... 


db.createUser({
	user:"antyrii",
	pwd: "99wcl34",
	roles:["readWrite", "dbAdmin" ]
})


//collections - tables in Relational DB

db.createCollection('customers');  //create table.. 
db.show collections  // show tables... 
db.customers.find();  //no need of creating an ID field... 

db.customers.insert({firstname:"amin", lastname:"man"}); //one record

//for multiple records and extra field on diff. columns.. 
db.customers.insert([{firstname:"mochacho", lastname:"ocholi"}, {firstname:"linda",lastname:"eno",gender:"female"}, {firstname:"okwuchi", lastname:"ugozie"},{firstname:"senora",lastname:"kme"}]);

//you can have an extra field on a column... 
db.customers.find().pretty() //helper function - to objects.. 

//updating fields...  update(criteriaKey, newObject) 
db.customers.update({firstname:"linda", {firstname:"andrea", gender:"male"}) //replaces the entire object.

db.customers.update({firstname:"okwuchi", {$set:{gender:"female"}})  //keep previous keys and update record.

//for interger values... 
db.customers.update({firstname:"senora", {$inc:{age:5}}) //find the record and increment the age by 5

//to remove a column... 
 db.customers.update({firstname:"mochacho"}, {$unset:{lastname:1}}) //use unset:field:1 // one
 
 //to update a record that isnt there... 
  db.customers.update({firstname:"mary"}, {firstname:"Marianne", gender:"male"}) 
  
  
 // -- returns 0,0,0 - unmatched... 
 // -- so if it isnt found - then insert it... 
  
  
 db.customers.update({firstname:"mary"}, {firstname:"Marianne", gender:"male"}, {upsert:true}) //to updateInsert it. 
 
 // To Remove Documents... 
 
 db.customers.remove({firstname:"Andrea"})
  db.customers.remove({firstname:"Andrea"}, {justOne:true) //just the first one..
  
 db.customers.find({$or:[{firstname:"okwuchi}, {firstname:"senora"}]}) //multiple fields & criteria.. 
 db.customers.find({age:{$gt:20}})  //>20 < 20, ~ gte, lte, gt, lt.
 
 
 
 db.customers.find({"address.city":"boston"})  // for object properties.. 
 
 //for array properties... 
 db.customers.find({membership:"mem1"})  //where membership is an array ["mem1","mem2","mem3"]
 
 
 db.customers.find(~).sort({lastname:1}) //ascending
 db.customers.find(~).sort({lastname:-1}) //descending
 
 db.customers.find(~).count(); // count documents... 
 db.customers.find(~).limit(4).sort({firstname:-1}); //limit 4 
 
db.customers.find().forEach(doc => print("Customer :: " + doc.firstname))