client and shell added

course/client/index.js

@@ -0,0 +1,37 @@
+// the client is the mongo shell
+
+// to watch all databases
+show dbs
+
+// to see current databse selected
+db
+
+// to select or create a database
+use mivirtualstore
+
+// CRUD OPERATIONS
+// TO CREATE
+
+const post = {
+  "title": "My first Post",
+  "content": "Here is my blog post",
+  "date": new Date()
+}
+// this generates an _id
+db.blog.insert(post) // WriteResult({ "nInserted" : 1 })
+
+// TO READ
+db.posts.find() // to query all collections
+db.posts.findOne() // to query a single collection
+
+// TO UPDATE
+// we need (criteria, newDocument)
+const myNewPost = db.posts.findOne()
+myNewPost.comments = [];
+db.posts.update(
+  {_id: ObjectId("5a2490f249c2a502853b7e7a")},
+  myNewPost
+) // this add comments: []
+
+// TO REMOVE
+db.posts.remove({title: "My first Post"})

course/collections/collection.js

@@ -1,11 +1,26 @@
 // is a group of documents
 // is equivalend of a table in SQL
 
-// have dynamic squemas
+// have DYNAMIC SQUEMAS
 // means the documents can be different inside of a collection
 // for example this could be stored in a single collection
 {"greeting": "Hello World"}
 {"foo": 5}
+
+// so why we need to separate collections
+// Keeping different kinds of documents in the same collection can be a nightmare
+// we need to make sure that each query is only returning documents of a certain type or that the application code performing a
+// • It is much faster to get a list of collections than to extract a list of the types in a  collection. For example, if we had a "type" field in each document that specified whether the document was a “skim,” “whole,” or “chunky monkey,” it would be much
+// slower to find those three values in a single collection than to have three separate collections and query the correct collection.
+// • Grouping documents of the same kind together in the same collection allows for
+// data locality. Getting several blog posts from a collection containing only posts will
+// likely require fewer disk seeks than getting the same posts from a collection con‐
+// taining posts and author data.
+// • We begin to impose some structure on our documents when we create indexes.
+// (This is especially true in the case of unique indexes.) These indexes are defined per
+// collection. By putting only documents of a single type into the same collection, we
+// can index our collections more efficiently.
+
 // these documents have diferent keys and value types
 
 // callection restrictions are:

course/readme.md

@@ -1,2 +1,4 @@
 # Course
 - document/
+- collections/
+- shell/

course/shell/index.js

@@ -0,0 +1,22 @@
+// to start the shell: mongo
+
+// the shell can be execute javascript
+x = 200;
+x / 5;
+
+// and we can use the standard javascript libraries
+Math.sin(Math.PI / 2)
+
+new Date("2018/1/1")
+
+"Hello World".replace("World, Mongodb");
+
+// and we can define functions
+function factorial(n) {
+  if (n <= 1) return 1;
+  return n * factorial(n - 1);
+}
+
+const double = n => n * 2;
+
+// and the shell also recongnise incomplete statments with ENTER

readme.md

@@ -8,9 +8,10 @@
 - orientado a documentos: document
 
 ## Comandos Usuales
+- to show mongodb version: 'mongod --version'
+- to show mongodb shell version: 'mongo --version'
 - to show a database: `show dbs`
 - to create a database: `use exampledatabase`
-- to show the current database: `db`
 
 - how to create a user: `db.createUser({})`
 - how to login with my user: `use database`, `db.auth("user","psw")`