mybatis如何实现saveOrUpdate

1. selectKey标签查询

DDL

CREATE TABLE `luck_reward_info` (
  `id` int NOT NULL AUTO_INCREMENT COMMENT 'id',
  `activity_id` varchar(20) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NOT NULL COMMENT '活动id',
  `reward_name` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci DEFAULT NULL COMMENT '奖品名',
  `reward_level` int DEFAULT NULL COMMENT '奖品等级',
  `num` int DEFAULT NULL COMMENT '奖品数量',
  `dis_number` int DEFAULT '0' COMMENT '已发奖品数量',
  `create_time` datetime DEFAULT NULL COMMENT '创建时间',
  `update_time` datetime DEFAULT NULL COMMENT '修改时间',
  `field` varchar(255) DEFAULT NULL COMMENT '备注',
  PRIMARY KEY (`id`,`activity_id`) USING BTREE
) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci ROW_FORMAT=DYNAMIC COMMENT='奖品信息表';

RewardInfoMapper接口

@Mapper
public interface RewardInfoMapper{
   int saveOrUpdate(RewardInfo rewardInfo);
}

使用selectKey

<insert id="saveOrUpdate" >
  <selectKey keyProperty="count" resultType="int" order="BEFORE">
    select count(*) from luck_reward_info where id = #{id}
  </selectKey>
  <if test="count > 0">
        UPDATE luck_reward_info
        <set>
            <if test='activityId != null and activityId != "" '>activity_id=#{activityId},</if>
            <if test='rewardName != null and rewardName != "" '>reward_name=#{rewardName},</if>
            <if test='rewardLevel != null '>reward_level=#{rewardLevel},</if>
            <if test='num != null '>num=#{num},</if>
            <if test='disNumber != null '>dis_number=#{disNumber},</if>
            update_time=now(),
            <if test='field != null and field != "" '>field=#{field},</if>
        </set>
        WHERE id=#{id}
  </if>
  <if test="count==0">
    INSERT INTO luck_reward_info(
            id,activity_id,reward_name,reward_level,number,create_time,field
            )
            VALUES (
            (select id from (select (ifnull(max(id), 0)) + 1 as id from luck_reward_info)t), #{activityId},#{rewardName},#{rewardLevel},#{number},now(),#{field}
            )
  </if>
</insert>

报错：

org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.executor.ExecutorException: No setter found for the keyProperty &lsquo;count&rsquo; in com.cmbchina.ssm.entity.RewardInfo.

原因：RewardInfo内必须有count属性，来接收count值，否则报错

优化：接口使用Map，实体类不需要再新增count字段了

//RewardInfoMapper.java
int saveOrUpdate(Map<String, Object> map);

2. 主键自增或者累加的，不使用selectKey

根据id是否为空，空新增，不为空修改

<insert id="saveOrUpdate" keyProperty="id" useGeneratedKeys="true">
        <if test="id == null">
            INSERT INTO luck_reward_info(
                id,activity_id,reward_name,reward_level,num,create_time,field
            )
            VALUES (
                (select id from (select (ifnull(max(id), 0)) + 1 as id from luck_reward_info)t), #{activityId},#{rewardName},#{rewardLevel},#{num},now(),#{field}
            )
        </if>
        <if test="id != null">
            UPDATE luck_reward_info
            <set>
                <if test='activityId != null and activityId != "" '>activity_id=#{activityId},</if>
                <if test='rewardName != null and rewardName != "" '>reward_name=#{rewardName},</if>
                <if test='rewardLevel != null '>reward_level=#{rewardLevel},</if>
                <if test='num!= null '>num=#{num},</if>
                <if test='disNumber != null '>dis_number=#{disNumber},</if>
                update_time=now(),
                <if test='field != null and field != "" '>field=#{field},</if>
            </set>
            WHERE id=#{id}
        </if>
    </insert>

3. 主键为varchar的使用ON DUPLICATE KEY UPDATE

DDL

CREATE TABLE `luck_activity_info` (
  `id` varchar(20) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NOT NULL COMMENT 'id',
  `title` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci DEFAULT NULL COMMENT '标题',
  `start_time` datetime DEFAULT NULL COMMENT '开始时间',
  `end_time` datetime DEFAULT NULL COMMENT '结束时间',
  `sap_id` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci DEFAULT NULL COMMENT '操作员工编号',
  `create_time` datetime DEFAULT NULL COMMENT '创建时间',
  `update_time` datetime DEFAULT NULL COMMENT '修改时间',
  PRIMARY KEY (`id`) USING BTREE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci ROW_FORMAT=DYNAMIC COMMENT='抽奖活动表';

条数 新增返回1，修改返回2

<insert id="saveOrUpdate">
        INSERT INTO luck_activity_info(
            id,title,start_time,end_time,sap_id,create_time
        )
        VALUES (
            #{id},#{title},#{startTime},#{endTime},#{sapId},now()
        )
        ON DUPLICATE KEY UPDATE
            <if test='title != null and title != "" '>title=#{title},</if>
            <if test='startTime != null '>start_time=#{startTime},</if>
            <if test='endTime != null '>end_time=#{endTime},</if>
            <if test='sapId != null and sapId != "" '>sap_id=#{sapId},</if>
            update_time=now()
    </insert>

来源：https://blog.csdn.net/m0_37539286/article/details/126594466