也许可以尝试使用与每个类别相关的子查询执行以下操作：

select category, (
  select product 
  from t t2 
  where t.category = t2.category
  order by rand() limit 1
) product
from t
group by category;

您可以按以下方式执行此操作：

SELECT t.category, t.product
FROM mytable t
inner join (
  select category, FLOOR((RAND() * (max(ID)-min(ID)+1))+min(ID)) as randomID
  from mytable
  group by category
) as s on s.category = t.category and s.randomID = t.ID

Demo here

另一种方法是使用PARTITION BY：

with tmp as (
select  row_number() over (partition by category 
                           order by RAND() 
                          ) as rn,
        category,
        product
from t
)
select  category , 
        product  
from tmp
where rn = 1