直接代码

SELECT
	id,
	koto 
FROM
	hitokoto 
WHERE
	koto IN ( SELECT t1.koto FROM hitokoto t1 GROUP BY t1.koto HAVING COUNT( 1 ) > 1 ) 
	AND id NOT IN ( SELECT MIN( id ) FROM hitokoto t1 GROUP BY t1.koto HAVING COUNT( 1 ) > 1 )

去除koto相同、留下id最小的。

查出相同的所有行，查出最小的那些，然后not in

好像有点慢。