mysql增加行数据

INSERT INTO users (username, email, password) VALUES ('john_doe', 'john@example.com', 'password123');

INSERT INTO users (username, email, password) VALUES 
('jane_doe', 'jane@example.com', 'password456'),
('jim_smith', 'jim@example.com', 'password789');

INSERT INTO user_profiles (user_id, first_name, last_name)
SELECT id, first_name, last_name FROM users WHERE role = 'admin';

-- 使用INSERT IGNORE忽略重复错误
INSERT IGNORE INTO users (username, email, password) VALUES ('john_doe', 'john@example.com', 'password123');

-- 使用REPLACE INTO替换重复记录
REPLACE INTO users (username, email, password) VALUES ('john_doe', 'john@example.com', 'password123');

-- 修改列的定义，增加长度
ALTER TABLE users MODIFY COLUMN email VARCHAR(255);