Mysql中如何删除表重复数据

DELETE
FROM
	table_name 
WHERE
	(字段1, 字段2) IN (
		SELECT
			t.字段1,
			t.字段2
		FROM
			(
				SELECT
					字段1,
					字段2
				FROM
					table_name 
				GROUP BY
					字段1,
					字段2
				HAVING
					count(1) > 1
			) t
	)
AND id NOT IN (
	SELECT
		dt.id
	FROM
		(
			SELECT
				min(id) AS id
			FROM
				table_name 
			GROUP BY
				字段1,
				字段2
			HAVING
				count(1) > 1
		) dt
)

create table new_table_temp

insert into new_table_temp

delete from table_name 

/*
 Navicat Premium Data Transfer
 Source Server         : localmysql
 Source Server Type    : MySQL
 Source Server Version : 80030
 Source Host           : localhost:3306
 Source Schema         : nie_db
 Target Server Type    : MySQL
 Target Server Version : 80030
 File Encoding         : 65001
 Date: 17/08/2022 10:49:41
*/
SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;
-- ----------------------------
-- Table structure for message
-- ----------------------------
DROP TABLE IF EXISTS `message`;
CREATE TABLE `message`  (
  `id` bigint(0) NOT NULL,
  `message_title` varchar(50) CHARACTER SET utf8mb3 COLLATE utf8mb3_general_ci NULL DEFAULT NULL,
  `message_context` varchar(200) CHARACTER SET utf8mb3 COLLATE utf8mb3_general_ci NULL DEFAULT NULL,
  `send_peo` bigint(0) NULL DEFAULT NULL,
  `receive_peo` bigint(0) NULL DEFAULT NULL,
  `scope` int(0) NULL DEFAULT 0,
  `del_flag` tinyint(0) NULL DEFAULT 0,
  `create_time` datetime(0) NULL DEFAULT NULL,
  `creator` tinyint(0) NULL DEFAULT NULL,
  `update_time` datetime(0) NULL DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8mb3 COLLATE = utf8mb3_general_ci ROW_FORMAT = Dynamic;
-- ----------------------------
-- Records of message
-- ----------------------------
INSERT INTO `message` VALUES (1, '测试消息', '消息内容', 23, 1231, 0, 0, '2022-08-17 10:39:51', 3, '2022-08-17 10:40:00');
INSERT INTO `message` VALUES (2, '测试消息', '消息内容', 23, 1231, 0, 0, '2022-08-17 10:39:51', 3, '2022-08-17 10:40:00');
INSERT INTO `message` VALUES (3, '测试消息', '消息内容', 23, 1231, 0, 0, '2022-08-17 10:39:51', 3, '2022-08-17 10:40:00');
INSERT INTO `message` VALUES (4, '测试消息', '消息内容', 23, 1231, 0, 0, '2022-08-17 10:39:51', 3, '2022-08-17 10:40:00');
SET FOREIGN_KEY_CHECKS = 1;

CREATE DEFINER=`root`@`localhost` PROCEDURE `remove`()
BEGIN
DECLARE count_all INT DEFAULT 0;
DECLARE count_copy INT DEFAULT 1;
-- 创建一个临时复制表,并将目标表数据复制进来
DROP TABLE if exists message_01 ;
create TEMPORARY TABLE message_01 (SELECT * FROM message);
-- 查询去重后实际条数 并赋值给我们的变量 去重根据实际需求更改GROUP BY 后面条件
SELECT COUNT(1) into count_all from (select COUNT(1) FROM message WHERE del_flag = 0 GROUP BY message_title,message_context) t ;
/*删除复制表的重复数据并保留一条  保留哪条数据可以自己根据条件调节，
比如最小id等等，就是条件问题 还有就是去重根据实际需求更改GROUP BY 后面条件
这里如果使用了逻辑删除，有需要保留数据的可以改成修改逻辑删除字段
*/
DELETE FROM message_01 WHERE ID NOT IN (
select t.id FROM (select MAX(id) as id FROM message WHERE del_flag = 0 GROUP BY message_title,message_context) t
);
-- 再次不去重查询 如结果和查询结果一样则操作正确且完整
select COUNT(1) INTO count_copy FROM message_01 WHERE del_flag = 0 ;
-- 进行最后两次查询结果比对
IF count_all = count_copy THEN
TRUNCATE message;
INSERT INTO message (SELECT * FROM message_01);
SELECT 'success';
ELSE 
SELECT '改造失败',count_all AS '原表条数',count_copy AS '复制表删除重复数据后统计的条数';
END IF;
END