CREATE TABLE student (
	student_id INT UNIQUE PRIMARY KEY,
	name VARCHAR(20) NOT NULL,
	major VARCHAR(20) DEFAULT 'undecided',
);

DESCRIBE student;
DROP TABLE student;

ALTER TABLE student ADD gpa DECIMAL(3,2);
ALTER TABLE student DROP COLUMN gpa;

INSERT INTO student VALUES(1, 'Jack', 'Biology')
INSERT INTO student(student_id, name) VALUES(2, 'Claire')

SELECT * FROM student;

UPDATE student
SET major = 'Bio'
WHERE major = 'Biology' OR major = 'Chemistry';

UPDATE student
SET name = 'Tom', major = 'undecided'
WHERE student_id = 1;

DELETE FROM student
WHERE student_id = 5;





QUERIES
-------


SELECT student_id, name
FROM student
ORDER BY name;         -- or ORDER BY id, name DESC; (descending)


SELECT *
FROM student
ORDER BY student_id, name DESC
LIMIT 2;


SELECT *
FROM student
WHERE major = 'Chemistry' OR name = 'Claire';

// <, >, =, <=, >=, <> (not equal), AND, OR

SELECT *
FROM student
WHERE student_id IN (1,4,5);



FOREIGN KEY(client_id) REFERENCES client(client_id) ON DELETE CASCADE;


SELECT first_name AS forename, last_name AS surname FROM employee;

SELECT DISTINCT sex FROM employee;  -- ola mia fora

SELECT emp.name, emp.id, branch.branch_name
FROM emp
JOIN branch
ON emp.id = branch.man_id;


SELECT emp.name
FROM emp
WHERE emp.id IN (
	SELECT works_with.emp_id
	FROM works_with
	WHERE works_with.sal > 30000
);