cs50 week 7 notes.txt

cs50 SQL notes

Spreadsheets strengths and weaknesses:
Strengths:
Good at sorting
Common to use
visual


Weaknesses:
Limits on amount of data you can use
Static schema

flat-file database:
	single, 1-file database. commonly CSV 

Lambda functions: One-line functions
Lambda functions are anonymous (nameless) functions
Still takes arguments, returns a value.
of the form:
lambda <arg>: <expression or value to return>
ex:
lamba x: x**2, takes x, returns x^2


relational databases:
SQLite
uses a single binary file to store all data
to interact with that blob, use sqlite3, a cli tool

loading data onto a sqlite db:
load via sqlite3
or, load via python

.mode (ex: .mode csv, or .mode xls, tsv (tab sep val))
.import <filename> <table name>

SQL: Structured Query Language, a language to maniuplate data
CRUD: Create, Read, Update, Delete

corresponding SQL commands for crud:
CREATE, INSERT (initialize table+data vs add data)
SELECT (in for read)
UPDATE
DELETE

sqlite3 commands start with a .
.mode <filetype>
.import <filename> <table name>
.schema: returns the CREATE TABLE command used

SQLite has 5 major datatypes:
blob ("Binary Large OBject")
integer (typically 32 bits)
numeric (Formatted numbers, like datetimes or bools)
real
text

Also has:
NOT NULL
UNIQUE
Primary and Foreign keys


Using Python and SQLite together:
import sqlite3