UPDATE your_table
SET comments = 'duplicate records'
WHERE (name, address, phone) IN (
SELECT name, address, phone
FROM your_table
GROUP BY name, address, phone
HAVING COUNT(*) > 1
);

这可以通过以下方式完成：
首先，我们需要每个组的最新记录：

select name, address, phone, max(id) as id
from mytable
group by name, address, phone
having count(*) > 1

然后我们使用left join来标识除该组的最新id之外的所有记录：

update mytable t
left join (
  select name, address, phone, max(id) as id
  from mytable
  group by name, address, phone
  having count(*) > 1
) as s on s.name = t.name and s.address = t.address and s.id = t.id
set t.comments = 'duplicate records'
where s.id is null

Demo here