mysql数据库建表id主键

-- 示例：插入重复主键
INSERT INTO users (id, name, email) VALUES (1, 'Alice', 'alice@example.com'); -- 会报错

-- 解决方法：使用自增主键
CREATE TABLE users (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(50),
    email VARCHAR(50) UNIQUE
);

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

-- 示例：分区表
CREATE TABLE orders (
    order_id INT,
    user_id INT,
    order_date DATE,
    PRIMARY KEY (order_id, user_id)
) PARTITION BY RANGE (YEAR(order_date)) (
    PARTITION p0 VALUES LESS THAN (2020),
    PARTITION p1 VALUES LESS THAN (2021),
    PARTITION p2 VALUES LESS THAN (2022),
    PARTITION p3 VALUES LESS THAN MAXVALUE
);