mysql重复数据查询删除

数据表

SUPPLIER_ID	COM_ID	SUPPLIER_NAME	OWNER_ID
1092002	1002001	上海飞科	3
1092003	1002001	上海飞科	3
9824001	28005	绍兴11	2
9824002	28005	绍兴11	2
9824003	28005	绍兴11	2
9824004	28006	绍兴12	2

1.查询重复记录（COM_ID,SUPPLIER_NAME,OWNER_ID）

SELECT
	*
FROM
	supplier_info
WHERE
	(
		COM_ID,
		owner_id,
		SUPPLIER_NAME
	) IN (
		SELECT
			COM_ID,
			owner_id,
			SUPPLIER_NAME
		FROM
			supplier_info
		GROUP BY
			COM_ID,
			owner_id,
			SUPPLIER_NAME
		HAVING
			count(1) > 1
	)

结果

SUPPLIER_ID	COM_ID	SUPPLIER_NAME	OWNER_ID
1092002	1002001	上海飞科	3
1092003	1002001	上海飞科	3
9824001	28005	绍兴11	2
9824002	28005	绍兴11	2
9824003	28005	绍兴11	2

2.删除重复记录（保留一条）

思路：先查询出要删除的记录id，然后删除。

查找需要删除的记录，重复记录里面id不在group_by里面的

SELECT
	*
FROM
	supplier_info
WHERE
	(
		COM_ID,
		owner_id,
		SUPPLIER_NAME
	) IN (
		SELECT
			COM_ID,
			owner_id,
			SUPPLIER_NAME
		FROM
			supplier_info
		GROUP BY
			COM_ID,
			owner_id,
			SUPPLIER_NAME
		HAVING
			count(1) > 1
	)
AND SUPPLIER_ID NOT IN (
	SELECT
		SUPPLIER_ID
	FROM
		supplier_info
	GROUP BY
		COM_ID,
		owner_id,
		SUPPLIER_NAME
	HAVING
		count(1) > 1
)

结果

SUPPLIER_ID	COM_ID	SUPPLIER_NAME	OWNER_ID
1092003	1002001	上海飞科	3
9824002	28005	绍兴11	2
9824003	28005	绍兴11	2

删除这些id的数据

DELETE
FROM
	supplier_info
WHERE
	supplier_id IN (
		SELECT
			SUPPLIER_ID
		FROM
			supplier_info
		WHERE
			(
				COM_ID,
				owner_id,
				SUPPLIER_NAME
			) IN (
				SELECT
					COM_ID,
					owner_id,
					SUPPLIER_NAME
				FROM
					supplier_info
				GROUP BY
					COM_ID,
					owner_id,
					SUPPLIER_NAME
				HAVING
					count(1) > 1
			)
		AND SUPPLIER_ID NOT IN (
			SELECT
				SUPPLIER_ID
			FROM
				supplier_info
			GROUP BY
				COM_ID,
				owner_id,
				SUPPLIER_NAME
			HAVING
				count(1) > 1
		)
	)

结果

查找原因发现是因为mysql不能用查询出来的数据去更新，解决方式将查询嵌套一层

DELETE
FROM
	supplier_info
WHERE
	supplier_id IN (
		SELECT
			supplier_id
		FROM
			(
				SELECT
					SUPPLIER_ID
				FROM
					supplier_info
				WHERE
					(
						COM_ID,
						owner_id,
						SUPPLIER_NAME
					) IN (
						SELECT
							COM_ID,
							owner_id,
							SUPPLIER_NAME
						FROM
							supplier_info
						GROUP BY
							COM_ID,
							owner_id,
							SUPPLIER_NAME
						HAVING
							count(1) > 1
					)
				AND SUPPLIER_ID NOT IN (
					SELECT
						SUPPLIER_ID
					FROM
						supplier_info
					GROUP BY
						COM_ID,
						owner_id,
						SUPPLIER_NAME
					HAVING
						count(1) > 1
				)
			) a
	)

删除成功结果

SUPPLIER_ID	COM_ID	SUPPLIER_NAME	OWNER_ID
1092002	1002001	上海飞科	3
9824001	28005	绍兴11	2
9824004	28006	绍兴12	2