某电商平台的数据分析师需要从订单表 orders 中为每个用户生成一个“消费等级”标签：消费总额大于10000元的标记为“高消费”，5000至10000元标记为“中消费”，低于5000元标记为“低消费”。分析师希望在新列 level 中展示该标签。以下SQL写法中，能正确实现该需求的是？
A. SELECT user_id, total_amount, IF(total_amount>10000,'高消费', total_amount>5000,'中消费','低消费') AS level FROM orders
B. SELECT user_id, total_amount, CASE WHEN total_amount>10000 THEN '高消费' WHEN total_amount>5000 THEN '中消费' ELSE '低消费' END AS level FROM orders
C. SELECT user_id, total_amount, CASE total_amount WHEN >10000 THEN '高消费' WHEN >5000 THEN '中消费' ELSE '低消费' END AS level FROM orders
D. SELECT user_id, total_amount, DECODE(total_amount, 10000, '高消费', 5000, '中消费', '低消费') AS level FROM orders
