オンラインMySQLエディタ

-- Basic SELECT query
SELECT 'Hello' AS greeting, 42 AS answer;

CREATE TABLE students (
  id INT AUTO_INCREMENT PRIMARY KEY,
  name VARCHAR(100) NOT NULL,
  age INT,
  grade DECIMAL(3,1)
);

INSERT INTO students (name, age, grade) VALUES
  ('Alice', 20, 3.8),
  ('Bob', 22, 3.5),
  ('Charlie', 21, 3.9);

SELECT * FROM students;

CREATE TABLE products (id INT AUTO_INCREMENT PRIMARY KEY, name VARCHAR(100), price DECIMAL(10,2), category VARCHAR(50));
INSERT INTO products (name, price, category) VALUES
  ('Laptop', 999.99, 'Electronics'),
  ('Book', 19.99, 'Education'),
  ('Phone', 699.99, 'Electronics');

SELECT name, price FROM products
WHERE price > 20 AND category = 'Electronics';

CREATE TABLE sales (product VARCHAR(50), region VARCHAR(50), amount DECIMAL(10,2));
INSERT INTO sales VALUES
  ('Widget', 'North', 100), ('Widget', 'South', 150),
  ('Gadget', 'North', 200), ('Gadget', 'South', 80);

SELECT product, SUM(amount) AS total
FROM sales
GROUP BY product
ORDER BY total DESC;

CREATE TABLE users (id INT AUTO_INCREMENT PRIMARY KEY, name VARCHAR(100), email VARCHAR(100));

INSERT INTO users (name, email) VALUES ('Alice', 'alice@example.com');
INSERT INTO users (name, email) VALUES ('Bob', 'bob@example.com');

UPDATE users SET email = 'alice@newmail.com' WHERE id = 1;

SELECT * FROM users;

CREATE TABLE scores (student VARCHAR(50), subject VARCHAR(50), score INT);
INSERT INTO scores VALUES
  ('Alice', 'Math', 92), ('Alice', 'Science', 88),
  ('Bob', 'Math', 78), ('Bob', 'Science', 95);

SELECT student,
  AVG(score) AS average,
  MAX(score) AS best,
  MIN(score) AS worst
FROM scores GROUP BY student;

CREATE TABLE employees (id INT, name VARCHAR(100), salary DECIMAL(10,2), dept VARCHAR(50));
INSERT INTO employees VALUES
  (1, 'Alice', 90000, 'Eng'), (2, 'Bob', 75000, 'Mktg'),
  (3, 'Charlie', 95000, 'Eng'), (4, 'Diana', 80000, 'Mktg');

SELECT name, salary FROM employees
WHERE salary > (SELECT AVG(salary) FROM employees);

CREATE TABLE orders (id INT AUTO_INCREMENT PRIMARY KEY, total DECIMAL(10,2), status VARCHAR(20));
INSERT INTO orders (total, status) VALUES
  (250, 'shipped'), (50, 'pending'), (500, 'delivered');

SELECT id, total,
  CASE
    WHEN total >= 200 THEN 'Large'
    WHEN total >= 100 THEN 'Medium'
    ELSE 'Small'
  END AS size
FROM orders;

CREATE TABLE users (name VARCHAR(50), email VARCHAR(100));
INSERT INTO users VALUES ('Alice', 'alice@example.com'), ('Bob', 'BOB@EXAMPLE.COM');

SELECT name, LOWER(email) AS email,
  LENGTH(name) AS name_length,
  CONCAT(name, ' <', LOWER(email), '>') AS formatted
FROM users;

CREATE TABLE depts (id INT, name VARCHAR(50));
INSERT INTO depts VALUES (1,'Engineering'),(2,'Marketing');

CREATE TABLE emps (id INT, name VARCHAR(50), dept_id INT, salary INT);
INSERT INTO emps VALUES (1,'Alice',1,90000),(2,'Bob',2,75000),(3,'Charlie',1,95000);

SELECT e.name, d.name AS department, e.salary
FROM emps e
INNER JOIN depts d ON e.dept_id = d.id
ORDER BY e.salary DESC;