CREATE DATABASE record_company;
USE record_company;
CREATE TABLE bands (
	id INT NOT NULL AUTO_INCREMENT ,
	name VARCHAR(255) NOT NULL , 
	PRIMARY KEY (id)
);
CREATE TABLE albums (
	id INT NOT NULL AUTO_INCREMENT ,
	name VARCHAR(255) NOT NULL , 
	release_year INT ,
	band_id INT NOT NULL ,
	PRIMARY KEY(id) ,
	FOREIGN KEY(band_id) REFERENCES bands(id)
);

INSERT INTO bands (name)
VALUES ('Iron Maden');
INSERT INTO bands (name)
VALUES ('Deuce'), ('Avenged Sevenfold'), ('Ankor');

SELECT * FROM bands;
SELECT * FROM bands LIMIT 2; --Afiseaza doar primele 2 linii
SELECT name FROM bands; --Doar coloana "name", fara "id"
SELECT id AS 'ID', name AS 'Band Name' FROM bands; --Se modifica numele coloanelor in tabel
SELECT * FROM bands ORDER BY name; --Nu vor mai fi ordonate dupa id, ci dupa nume
SELECT * FROM bands ORDER BY name DESC;

INSERT INTO albums (name, release_year, band_id)
VALUES	('The Number of the Beasts', 1985, 1),
		('Power Slave', 1984, 1),
		('Nightmare', 2018, 2),
		('Nightmare', 2010, 3),
		('Test Album', NULL, 3);
SELECT * FROM albums;
SELECT DISTINCT name FROM albums; --Doar numele unice

UPDATE albums
SET release_year = 1982 WHERE id = 1;

SELECT * FROM albums
WHERE release_year < 200;

SELECT * FROM albums
WHERE name LIKE '%er%' --Trebuie ca numele sa aiba er inauntru
OR band_id = 2;

SELECT * FROM albums 
WHERE release_year = 1984 AND band_id = 1;

SELECT * FROM albums
WHERE release_year BETWEEN 2000 AND 2018;

SELECT * FROM albums
WHERE release_year IS NULL;

DELETE FROM albums WHERE id = 5;

SELECT * FROM albums;

SELECT * FROM bands 
JOIN albums ON bands.id = albums.id 

SELECT AVG(release_year) FROM albums;

SELECT band_id, COUNT(band_id) FROM albums
GROUP BY band_id; 

SELECT b.name AS band_name, COUNT (a.id) AS num_albums
FROM bands AS b
LEFT JOIN albums AS a ON b.id = a.band_id
WHERE b.name = 'Deuce'
GROUP BY b.id
HAVING num_albums = 1;