MyBatis新增数据时自增id的两种写法

一、单个插入

• 接口方法：

        public interface PlayerDao {
            int insertOnePlayer(Player player);
            int insertOnePlayer2(Player player);
        }

1.1 方式一

       public void testInsertGenerateId1() throws IOException {
               // 2.获取sqlSession
               SqlSession sqlSession = sqlSessionFactory.openSession();
               // 3.获取对应mapper
               PlayerDao mapper = sqlSession.getMapper(PlayerDao.class);
               // 4.执行查询语句并返回结果
               Player player = new Player();
               player.setPlayName("Allen Iverson");
               player.setPlayNo(3);
               player.setTeam("76ers");
               player.setHeight(1.83F);
               mapper.insertOnePlayer(player);
               sqlSession.commit();
               System.out.println(player.getId());
           }

• Mapper文件：

          <insert id="insertOnePlayer" parameterType="Player" useGeneratedKeys="true" keyProperty="id">
         		insert into tb_player (id, playName, playNo,team, height)
         		values (
                     #{id,jdbcType=INTEGER},
                     #{playName,jdbcType=VARCHAR},
                     #{playNo,jdbcType=INTEGER},
                     #{team,jdbcType=VARCHAR},
                     #{height,jdbcType=DECIMAL}
         		)
         	</insert>

• 方式一配置：useGeneratedKeys=“true” keyProperty=“id” 即可

1.2 方式二

        public void testInsertGenerateId2() throws IOException {
                // 2.获取sqlSession
                SqlSession sqlSession = sqlSessionFactory.openSession();
                // 3.获取对应mapper
                PlayerDao mapper = sqlSession.getMapper(PlayerDao.class);
                // 4.执行查询语句并返回结果
                Player player = new Player();
                player.setPlayName("Tony Parker");
                player.setPlayNo(9);
                player.setTeam("spurs");
                player.setHeight(1.88F);
                mapper.insertOnePlayer2(player);
                sqlSession.commit();
                System.out.println(player.getId());
            }
        
        
        Mapper文件：
       <insert id="insertOnePlayer2" parameterType="Player">
               <selectKey  keyProperty="id" order="AFTER" resultType="int">
                   select LAST_INSERT_ID()
               </selectKey>
               insert into tb_player (id, playName, playNo,team, height)
               values (
               #{id,jdbcType=INTEGER},
               #{playName,jdbcType=VARCHAR},
               #{playNo,jdbcType=INTEGER},
               #{team,jdbcType=VARCHAR},
               #{height,jdbcType=DECIMAL}
               )
           </insert>

• 方式二通过 selectKey 标签完成 ,selectKey 更加灵活，支持一定程度的自定义

二、批量插入

• Java文件省略了，这里直接给出Mapper文件， Mapper 文件如下，其实就是：useGeneratedKeys=“true” keyProperty=“id”，其中id是JavaBean的主键id

      <insert id="insertBatch" parameterType="java.util.List" useGeneratedKeys="true" keyProperty="id">
       INSERT INTO partition_info (id, node_ip_id, init_schema_info_id,
       prefix_table_index, partition_num, start_time,
       end_time, create_time, is_delete
       )
       values
       <foreach collection="list" item="item" index="index" separator=",">
         (#{item.id,jdbcType=INTEGER}, #{item.nodeIpId,jdbcType=INTEGER}, #{item.initSchemaInfoId,jdbcType=INTEGER},
         #{item.prefixTableIndex,jdbcType=VARCHAR}, #{item.partitionNum,jdbcType=VARCHAR}, #{item.startTime,jdbcType=TIMESTAMP},
         #{item.endTime,jdbcType=TIMESTAMP}, #{item.createTime,jdbcType=TIMESTAMP}, #{item.isDelete,jdbcType=TINYINT}
         )
       </foreach>
     </insert>

• Java代码

            System.out.println("before insert ...");
            for (PartitionInfo p: list) {
                System.out.println(p);
            }
    
            PartitionInfoMapper mapper = sqlSession.getMapper(PartitionInfoMapper.class);
            int i = mapper.insertBatch(list);
            System.out.println("The rows be affected :" + i);
    
            System.out.println("after insert ...");
            for (PartitionInfo p: list) {
                System.out.println(p);
            }

• 输出

    before insert ...
    PartitionInfo(id=null, nodeIpId=1, initSchemaInfoId=1, prefixTableIndex=1, partitionNum=null, startTime=null, endTime=null, createTime=Fri Dec 13 18:26:46 CST 2019, isDelete=null)
    PartitionInfo(id=null, nodeIpId=2, initSchemaInfoId=2, prefixTableIndex=2, partitionNum=null, startTime=null, endTime=null, createTime=Fri Dec 13 18:26:46 CST 2019, isDelete=null)
    PartitionInfo(id=null, nodeIpId=3, initSchemaInfoId=3, prefixTableIndex=3, partitionNum=null, startTime=null, endTime=null, createTime=Fri Dec 13 18:26:46 CST 2019, isDelete=null)
    The rows be affected :3
    after insert ...
    PartitionInfo(id=701, nodeIpId=1, initSchemaInfoId=1, prefixTableIndex=1, partitionNum=null, startTime=null, endTime=null, createTime=Fri Dec 13 18:26:46 CST 2019, isDelete=null)
    PartitionInfo(id=702, nodeIpId=2, initSchemaInfoId=2, prefixTableIndex=2, partitionNum=null, startTime=null, endTime=null, createTime=Fri Dec 13 18:26:46 CST 2019, isDelete=null)
    PartitionInfo(id=703, nodeIpId=3, initSchemaInfoId=3, prefixTableIndex=3, partitionNum=null, startTime=null, endTime=null, createTime=Fri Dec 13 18:26:46 CST 2019, isDelete=null)

• 这里其他的代码都省略了，基本上就是： useGeneratedKeys=“true” keyProperty=“id” 这两个标签起作用
• 另外我用的mybatis版本是 3.4.1

三、注意

• 注意Mapper文件中的 insert into tb_player (id, playName, playNo,team, height)，这里不要多了一个逗号，之前height后面还有一个逗号导致一直空指针的错误。