关于mysql的一些额外的了解

1.本文介绍：处理用户重复点击引发事务幻读的问题

2.场景： service逻辑(获取远端接口数据保存于本地临时表，首先需要删除表中数据，然后批量添加数据(跟数据量无关)，最后分页查询返回给界面)

3.实验结果：

　　关闭自动提交，数据库默认引擎innodb，事务默认隔离级别可重复读（不会出现脏读，不可重复读（两次结果不一样），会出现幻读）

操作语句：

1 select count(*) from sys_person_consumer_order_temp;
2 delete from sys_person_consumer_order_temp;
3 INSERT INTO `sys_person_consumer_order_temp`(`order_no`,`name`,`work_code`,`card_no`,`trade_amount`,`status`,`trade_date`,`merch_no`,`merch_name`,`remark`,`update_time`) VALUES ('9000024520190520180557208038', '嘉联测试卡B', '900087', '570579026', 100, 'S', '20190520180557', '84961015943A000', '诚意金测试---勿动', '记账成功', '20190520180557');
4 INSERT INTO `sys_person_consumer_order_temp`(`order_no`,`name`,`work_code`,`card_no`,`trade_amount`,`status`,`trade_date`,`merch_no`,`merch_name`,`remark`,`update_time`) VALUES ('9000024520190520180430873158', '嘉联测试卡B', '900087', '570579026', 100, 'S', '20190520180430', '84961015943A000', '诚意金测试---勿动', '记账成功', '20190520180431');
5 select count(*) from sys_person_consumer_order_temp ;

 1 DROP TABLE IF EXISTS `sys_person_consumer_order_temp`;
 2 CREATE TABLE `sys_person_consumer_order_temp`  (
 3   `id` int(11) UNSIGNED ZEROFILL NOT NULL AUTO_INCREMENT,
 4   `order_no` char(32) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT '',
 5   `name` varchar(20) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL,
 6   `work_code` char(8) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL COMMENT '员工工号',
 7   `card_no` char(10) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL COMMENT '会员卡号',
 8   `trade_amount` int(15) UNSIGNED DEFAULT NULL COMMENT '交易金额',
 9   `status` char(2) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL,
10   `trade_date` char(20) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL COMMENT '交易日期',
11   `merch_no` char(25) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT '',
12   `merch_name` char(30) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL,
13   `remark` varchar(50) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL COMMENT '备注',
14   `update_time` varchar(20) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL,
15   PRIMARY KEY (`id`) USING BTREE,
16   INDEX `orderno`(`order_no`) USING BTREE
17 ) ENGINE = InnoDB AUTO_INCREMENT = 604788 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Compact;

多次查询，结果不一致

解决思路：

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1.引发死锁（开始清空数据库，因为是临时表开始无所谓数据） service查询后再去清空数据

1 select count(*) from sys_person_consumer_order_temp;
2 INSERT INTO `sys_person_consumer_order_temp`(`order_no`,`name`,`work_code`,`card_no`,`trade_amount`,`status`,`trade_date`,`merch_no`,`merch_name`,`remark`,`update_time`) VALUES ('9000024520190520180557208038', '嘉联测试卡B', '900087', '570579026', 100, 'S', '20190520180557', '84961015943A000', '诚意金测试---勿动', '记账成功', '20190520180557');
3 INSERT INTO `sys_person_consumer_order_temp`(`order_no`,`name`,`work_code`,`card_no`,`trade_amount`,`status`,`trade_date`,`merch_no`,`merch_name`,`remark`,`update_time`) VALUES ('9000024520190520180430873158', '嘉联测试卡B', '900087', '570579026', 100, 'S', '20190520180430', '84961015943A000', '诚意金测试---勿动', '记账成功', '20190520180431');
4 select count(*) from sys_person_consumer_order_temp ;
5 delete from sys_person_consumer_order_temp;（第一个事务不提交，第二个事务会阻塞）

判断死锁

第二种思路：

不修改service逻辑

加入 select.... for update

关于mysql的一些额外的了解

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