sql

查找重复的电子邮箱

SELECT email FROM person GROUP BY email HAVING sum(1) > 1;

删除重复的电子邮箱

DELETE p1.* FROM person p1, person p2 WHERE p1.email = p2.email AND p1.id > p2.id;

创建表

CREATE TABLE IF NOT EXISTS table (
    id INT PRIMARY KEY AUTO_INCREMENT COMMENT '主键',
    name VARCHAR(50) NOT NULL,
    gender ENUM(0, 1, 2) NOT NULL,
    age INT NOT NULL,
    create_at DATETIME DEFAULT CURRENT_DATETIME
)