learning.sql

-- CREATE TABLE
--@block
CREATE TABLE IF NOT EXISTS users(
    id INT PRIMARY KEY AUTO_INCREMENT,
    name VARCHAR(255) NOT NULL UNIQUE,
    age INT NOT NULL,
    password VARCHAR(255) NOT NULL
);
-- INSERT DATA
--@block
INSERT INTO users (name, age, password)
VALUES ('Jane', 21, '12345'),
    ('John', 44, '12345'),
    ('Jowei', 14, '12345'),
    ('Ann', 18, '12345');
-- ADD COLUMNS
--@block
ALTER TABLE users
ADD COLUMN date INT;
-- UPDATE DATA
--@block
UPDATE users
SET name = 'Kamaa'
WHERE id = 2;
-- DELETE
--@block
DELETE FROM users
WHERE id = 4;
-- READ DATA
--@block
SELECT *
FROM users;
-- SORT
--@block
SELECT *
FROM users
WHERE age > 18
ORDER BY age DESC;
-- FILTER
--@block
SELECT *
FROM users
WHERE id > 1
    AND name LIKE 'J%';
--@block
ALTER TABLE users DROP COLUMN date;
--@block
DROP TABLE users;
--@block
CREATE TABLE IF NOT EXISTS rooms (
    id INT PRIMARY KEY AUTO_INCREMENT,
    hotel_name VARCHAR(255) NOT NULL UNIQUE,
    floor INT NOT NULL,
    owner_id INT NOT NULL,
    FOREIGN KEY (owner_id) REFERENCES users(id) ON DELETE CASCADE
);
--@block
INSERT INTO rooms (hotel_name, floor, owner_id)
VALUES ('Kilimanjaro', 12, 3),
    ('Tsavo', 1, 2),
    ('Githu', 1, 4),
    ('Kaka', 2, 3);
--@block
SELECT *
FROM rooms;
--@block
DROP TABLE rooms;
--@block
SELECT *
FROM users
    INNER JOIN rooms ON rooms.owner_id = users.id;