掌握UPDATE语法：轻松高效更新数据库，告别繁琐操作

UPDATE 表名 SET 列名 = 新值 WHERE 条件;

UPDATE employees SET salary = salary * budget_table.raise_rate FROM budget_table WHERE employees.dept_id = budget_table.dept_id AND budget_table.year = 2024;

UPDATE users u JOIN user_profiles up ON u.id = up.user_id SET u.last_login = NOW(), up.login_count = up.login_count + 1 WHERE u.username = 'john_doe';

UPDATE users SET status = 'inactive';

-- 首先处理普通商品 UPDATE products SET price = ROUND(price * 0.8, 2),

updated_at = GETDATE()

WHERE status = 'active' AND category_id IN (1, 2, 3) AND promotional_price IS NULL;

-- 然后处理特殊商品 UPDATE products SET promotional_price = ROUND(price * 0.75, 2) WHERE is_premium = 1 AND stock_quantity > 0;