mysql 如何查询唯一且最小值？

Question

比如表a如下结构
id score
1 1
2 1
3 2
4 4

我要查询score首先唯一（不重复），（然后）且为最小，返回的正确结果id应该就是3

那么sql语句该怎么写呢？请教大神。

Answer 1

SELECT id, score from table GROUP BY score HAVING COUNT(score) = 1 ORDER BY score LIMIT 1

Answer 2

SELECT id FROM table where score = (select score from table GROUP BY score HAVING COUNT(score) = 1 ORDER BY score LIMIT 1)