我的解决方案有问题，我发现以下示例：
(SELECT COUNT(*) FROM person AS b
WHERE b.group = a.group AND b.age >= a.age) <= 2
ORDER BY a.group ASC, a.age DESC
（来自：获取每组分组结果的前n条记录）
但是我需要在旧的基础上创建新的列，所以我需要做一些计算，当我试图添加更多的东西时，我会收到错误消息。如果我简单地添加eaquations，就可以了，例如：
(SELECT COUNT(*) FROM person AS b
WHERE b.group = a.group AND b.age*100 >= a.age*100) <= 2
ORDER BY a.group ASC, a.age DESC
但是当我试图重命名我的新专栏时，有太多的AS。
我还尝试使用UNIONALL，但我的SQLite对（）不满意。这对我根本不起作用：
(
select *
from mytable
where `year` = 2012
order by score*100/50 AS percent desc
LIMIT 2
)
UNION ALL
(
select *
from mytable
where `year` = 2013
order by score*100/50 AS percent desc
LIMIT 2
)
“结果：在第1行：
（”附近：语法错误
）
即使当我在（）之前取出SELECT和from时，我也会得到错误消息。
select * from mytable
(where `year` = 2012
order by score*100/50 AS percent desc
LIMIT 2)
UNION ALL
select * from mytable
(where `year` = 2013
order by score*100/50 AS percent desc
LIMIT 2)
靠近“WHERE”：语法错误
有人能解释一下为什么吗？
编辑
这是数据。
| Person | Year | Score | +--------+-------+-------+ | Bob | 2013 | 32 | | Jill | 2012 | 34 | | Shawn | 2012 | 42 | | Jake | 2012 | 29 | | Paul | 2013 | 36 | | Laura | 2013 | 39 |
期望结果集：
| Person | Year | Percent | +--------+-------+---------+ | Shawn | 2012 | 84 | | Jill | 2012 | 68 | | Laura | 2013 | 78 | | Paul | 2013 | 72 | +--------+-------+---------+
其中百分比=分数*100/50
此语法应该工作：
select *
from (
select *
from mytable
where `group` = 1
order by age desc
LIMIT 2
)
UNION ALL
select *
from (
select *
from mytable
where `group` = 2
order by age desc
LIMIT 2
);
但您也可以使用ROW_NUMBER（）执行此操作：
select t.`group`, t.age, ....<rest of the columns from mytable>
from (
select *, row_number() over (partition by `group` order by age desc) rn
from mytable
where `group` in (1, 2)
) t
where t.rn <= 2
