Wk2Day4Notes

Wk2Day4Notes

What problem does Git solve?

*Data backup
*Remote access


What is version control?

Reference older versions of your code. 

C reate  a = [2, 11, 37. 42]
R ead    a.map!do|x|   
U pdate (map) x + 5
D estroy a = nil

RESTful/CRUD

GET - Read
POST - Create
PUT - Replace
PATCH - Merge
DELETE - Destroy

get "/movies"
get "/movies/:id"
post "/movies"
patch "/movies/:id"


Everything in a database has its own id. The exception is a problem created unintentionally. 


CRUD pattern is everywhere. The purpose of a database is to store and retrieve data.



Databases

*CRUD
*Create, Read, Update, Destroy
(siderant: Apache graveyard is where open source projects go to die.)


Brands
Mongo, SQLite, Postgres, Couch, BerkleyDB, Oracle




Types of databases

JSON
Relation
SQL
XML
Spreadsheet


SQL, Structured Query Langue / Relation Algebra

===


CRUD

INSERT, SELECT, UPDATE, DELETE

*Class  - Tables
*Arrays - result set (several rows)
*Hash (instance) - row
*Keys (properties, attributes) - field names
*Values (properties, attributes) - fileds



CREATE TABLE movies (
    title TEXT
  , desc  TEXT
  , 
)



SQLITE3 = allows us to talk to SQLITE (Excel)
SQL = language
SQLITE = database management system
Schema = another word for structure in the database; a word for the way things work together

INSERT INTO = the create method in SQL
SELECT *FROM = will "get" all the fields from a single class


.read, .schema -- specific to SQLITE


SELECT * FROM WHERE GROUP BY HAVING
SELECT * FROM WISHLISTS
SELECT name,price,on_sale FROM products WHERE price < 10;