moving/deleting files

4. MySQL.md

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-# MySQL Bootcamp
-
-## Lesson Objectives
-
-1. What is a DB?
-1. What are the different ways to store data?
-1. What are the advantages of a database?
-1. What does SQL Stand for?  What is it?
-1. Diagram MySQL structure
-
-```sql
--- CREATE DB/TABLES
-SHOW DATABASES;
-CREATE DATABASE our_database_name;
-USE our_database_name;
-CREATE TABLE people (first_name VARCHAR(20), age INT);
-DESCRIBE people;
-
--- CRUD
-INSERT INTO people (first_name, age) VALUES ('Matt' , 34);
-SELECT age FROM people;
-SELECT * FROM people;
-UPDATE people SET weight = 300 WHERE first_name = 'Bill';
-DELETE FROM people WHERE first_name = "Bill";
-
--- OPERATORS
-SELECT * FROM people WHERE age != 63;
-SELECT * FROM people WHERE age < 63;
-SELECT * FROM people WHERE age > 63;
-SELECT * FROM people WHERE age >= 63;
-SELECT * FROM people WHERE age <= 63;
-SELECT * FROM people WHERE first_name first_name LIKE "%Charlie%";
-SELECT * FROM people WHERE first_name NOT LIKE "%Charlie%";
-SELECT * FROM people WHERE age IS NULL;
-SELECT * FROM people WHERE age IS NOT NULL;
-
-
--- AND/OR
-SELECT * FROM people WHERE first_name = 'Matt' AND age = 43;
-SELECT * FROM people WHERE first_name = 'Matt' OR age = 49;
-
--- ORDER
-SELECT * FROM people ORDER BY age DESC;
-SELECT * FROM people ORDER BY first_name DESC;
-SELECT * FROM people ORDER BY age ASC LIMIT 2;
-SELECT * FROM people ORDER BY age ASC LIMIT 2 OFFSET 1;
-SELECT * FROM people ORDER BY age DESC, first_name ASC;
-
--- ALTER TABLE
-ALTER TABLE people ADD COLUMN weight FLOAT;
-ALTER TABLE people DROP COLUMN height;
-ALTER TABLE people MODIFY COLUMN height FLOAT;
-
-ALTER TABLE people ADD COLUMN height FLOAT AFTER first_name;
-ALTER TABLE people MODIFY COLUMN height FLOAT AFTER age;
-
-ALTER TABLE people ADD COLUMN id INT FIRST;
-ALTER TABLE people MODIFY COLUMN height FLOAT FIRST;
-
-ALTER TABLE people ADD COLUMN dob DATETIME;
-ALTER TABLE people CHANGE dob date_of_birth DATETIME;
-
-ALTER TABLE people ADD COLUMN id INT NOT NULL AUTO_INCREMENT PRIMARY KEY FIRST;
-
--- AGGREGATION
-SELECT COUNT(*), age FROM people GROUP BY age;
-SELECT SUM(salary), age FROM people GROUP BY age;
-SELECT AVG(salary), age FROM people GROUP BY age;
-SELECT MIN(salary), age FROM people GROUP BY age;
-SELECT MAX(salary), age FROM people GROUP BY age;
-SELECT GROUP_CONCAT(first_name), age FROM people GROUP BY age;
-SELECT GROUP_CONCAT(first_name), age, height FROM people GROUP BY age, height;
-
--- JOINS
-SELECT * FROM people JOIN companies ON people.employer_id = companies.id;
-SELECT * from people JOIN companies;
-SELECT * FROM people RIGHT JOIN companies ON people.employer_id = companies.id;
-SELECT * FROM people LEFT JOIN companies ON people.employer_id = companies.id;
-```