MYSQL指令合集一文详解

SELECT * FROM table_name;
SELECT name, age FROM users;
SELECT * FROM users WHERE id = 1;
SELECT * FROM users WHERE name = 'Elias';

INSERT INTO users(name, age) VALUES ('Jack', 20);
INSERT INTO users(id, name, age) VALUES (1, 'Lily', 22);

INSERT INTO users(name, age)
VALUES ('A', 10), ('B', 20), ('C', 30);

UPDATE users SET age = 25 WHERE id = 1;
UPDATE users SET name = 'Mike', age = 18 WHERE id = 2;

DELETE FROM users WHERE id = 1;
DELETE FROM users WHERE age < 10;

CREATE TABLE users (
    id INT PRIMARY KEY AUTO_INCREMENT,
    name VARCHAR(50) NOT NULL,
    age INT
);

DROP TABLE users;

ALTER TABLE users ADD email VARCHAR(100);

ALTER TABLE users DROP COLUMN email;

ALTER TABLE users MODIFY age INT NOT NULL;

ALTER TABLE users RENAME TO members;

SELECT * FROM users WHERE age >= 18;
SELECT * FROM users WHERE age BETWEEN 18 AND 30;
SELECT * FROM users WHERE name LIKE 'A%';   -- A 开头
SELECT * FROM users WHERE name LIKE '%abc%'; -- 包含 abc
SELECT * FROM users WHERE age IN (18, 20, 25);
SELECT * FROM users WHERE age IS NULL;
SELECT * FROM users WHERE age IS NOT NULL;

SELECT * FROM users WHERE age > 18 AND name = 'Jack';
SELECT * FROM users WHERE age < 18 OR age > 60;

SELECT * FROM users ORDER BY age DESC;
SELECT * FROM users ORDER BY age ASC, name ASC;

SELECT * FROM users LIMIT 10;        -- 前 10 条
SELECT * FROM users LIMIT 5 OFFSET 10;

SELECT * FROM users LIMIT (page-1)*size, size;

SELECT u.name, o.order_id
FROM users u
JOIN orders o ON u.id = o.user_id;

SELECT u.name, o.order_id
FROM users u
LEFT JOIN orders o ON u.id = o.user_id;

SELECT u.name, o.order_id
FROM users u
RIGHT JOIN orders o ON u.id = o.user_id;

SELECT age, COUNT(*) 
FROM users 
GROUP BY age;

SELECT age, COUNT(*) AS cnt
FROM users
GROUP BY age
HAVING cnt >= 2;

SELECT AVG(age) FROM users;
SELECT SUM(age), MIN(age), MAX(age) FROM users;

SELECT * FROM users 
WHERE age > (SELECT AVG(age) FROM users);
SELECT name FROM users 
WHERE id IN (SELECT user_id FROM orders);

CREATE INDEX idx_name ON users(name);

DROP INDEX idx_name ON users;

CREATE UNIQUE INDEX idx_email ON users(email);

PRIMARY KEY (id)

UNIQUE(email)

CONSTRAINT fk_user
FOREIGN KEY(user_id) REFERENCES users(id)

START TRANSACTION;

UPDATE users SET age = age - 1 WHERE id = 1;
UPDATE users SET age = age + 1 WHERE id = 2;

COMMIT;

ROLLBACK;

USE dbname;

SHOW DATABASES;

SHOW TABLES;

DESC users;

SET NAMES utf8mb4;

mysql_options(conn, MYSQL_SET_CHARSET_NAME, "utf8mb4");

CREATE TABLE user(
    id INT PRIMARY KEY AUTO_INCREMENT,
    name VARCHAR(50) UNIQUE,
    password VARCHAR(100),
    create_time TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);
INSERT INTO user(name, password) VALUES ('Elias', '123456');
SELECT id, name FROM user WHERE name='Elias' AND password='123456';