SQL删除表中的重复记录（多个字段），只留一条。

在一家韩国电商的面试中被问到了，当时一脸懵逼，没想法……

回来想了想，还是有些思路的……唉……临场真是弱啊……

第一步：查询重复记录

SELECT * FROM TableName
WHERE RepeatFiled IN (
	SELECT RepeatFiled
	FROM TableName
	GROUP BY RepeatFiled
	HAVING COUNT(RepeatFiled) > 1
)

这一段逻辑很简单，就是把重复条数大于1的全部都搞出来就行了。

第二步：删除重复记录，只保留一条

SELECT * FROM TableName
WHERE RepeatFiled IN (
	SELECT RepeatFiled
	FROM TableName
	GROUP BY RepeatFiled
	HAVING COUNT(RepeatFiled) > 1
	AND
	ID NOT IN (
		SELECT MIN(ID)
		FROM TableName
		GROUP RepeatFiled
		HAVING COUNT(RepeatFiled) > 1	
	)
)

在上一步的基础上继续过滤，那就把最小值留下就行了，大功告成！