Mybatis批量添加、更新小结

虽然是很基础的东西，不过难免会忘记，所以写个笔记巩固一下，顺便分享。

实体类：

@Data
public class EventOrder {
​
    private Long id;
​
    private String eventName;
​
    private Integer eventType;
​
    private String orderNo;
​
}

表字段：

批量添加

<sql id="BaseColumn">
        `id`, event_name, event_type, order_no
    </sql>

    <insert id="batchInsertByValues" parameterType="com.zyuan.boot.entity.EventOrder">
        insert into event_order
        (<include refid="BaseColumn"/>)
        values
        <foreach collection="eventOrders" item="item" separator=",">
            (
            #{item.id}, #{item.eventName}, #{item.eventType}, #{item.orderNo}
            )
        </foreach>
    </insert>

< foreach >标签中，collection表示传入的集合名，item为每个元素，separator为分隔符

xml对应的mapper文件中最好加上@Param注解，保证准确性：

void batchInsertByValues(@Param("eventOrders") List<EventOrder> eventOrders);

测试：

@Autowired
private EventOrderMapper eventOrderMapper;
​
@Test
public void batchInsertByValues() {
    List<EventOrder> eventOrders = getList();
    eventOrderMapper.batchInsertByValues(eventOrders);
}
​
private List<EventOrder> getList() {
    List<EventOrder> eventOrders = new ArrayList<>();
    for (Long i = 1L; i <= 10; i++) {
        EventOrder addEntity = new EventOrder();
        addEntity.setId(i);
        addEntity.setEventName("事件" + i);
        addEntity.setEventType(1);
        addEntity.setOrderNo("2");
        eventOrders.add(addEntity);
    }
    return eventOrders;
}

打印的sql语句：

INSERT INTO event_order ( `id`, event_name, event_type, order_no )
VALUES
    ( ?, ?, ?, ? ),
    ( ?, ?, ?, ? ),
    ( ?, ?, ?, ? ),
    ( ?, ?, ?, ? ),
    ( ?, ?, ?, ? ),
    ( ?, ?, ?, ? ),
    ( ?, ?, ?, ? ),
    ( ?, ?, ?, ? ),
    ( ?, ?, ?, ? ),
    ( ?, ?, ?, ? )

批量更新

<update id="batchUpdate" parameterType="com.zyuan.boot.entity.EventOrder">
    update event_order
    <trim prefix="set" suffixOverrides=",">
        <trim prefix="event_name = case" suffix="end,">
            <foreach collection="eventOrders" item="item">
                when `id` = #{item.id} then #{item.eventName}
            </foreach>
        </trim>
        <trim prefix="event_type = case" suffix="end,">
            <foreach collection="eventOrders" item="item">
                when `id` = #{item.id} then #{item.eventType}
            </foreach>
        </trim>
        <trim prefix="order_no = case" suffix="end">
            <foreach collection="eventOrders" item="item">
                when `id` = #{item.id} then #{item.orderNo}
            </foreach>
        </trim>
    </trim>
    where id in
    <foreach collection="eventOrders" item="item" open="(" close=")" separator=",">
        #{item.id}
    </foreach>
</update>

解释：第一个< trim >用于拼接set前缀以及标签中所有< trim >连接的 “,” ，然后里面的< trim >，prefix存放的是：“被修改字段” + “=” + “case” ，suffix存放的是case的终止关键字end，foreach是为了遍历出所有id的情况并通过then来给值。

打印sql：

UPDATE event_order 
SET 
event_name =
    CASE
        WHEN `id` = ? THEN ? 
        WHEN `id` = ? THEN ? 
        WHEN `id` = ? THEN ? 
        WHEN `id` = ? THEN ? 
    END,
​
event_type =
    CASE
        WHEN `id` = ? THEN ? 
        WHEN `id` = ? THEN ? 
        WHEN `id` = ? THEN ? 
        WHEN `id` = ? THEN ? 
    END,
    
order_no =
    CASE
        WHEN `id` = ? THEN ? 
        WHEN `id` = ? THEN ? 
        WHEN `id` = ? THEN ? 
        WHEN `id` = ? THEN ? 
    END 
WHERE
    id IN ( ?, ?, ?, ? )

还有一种通过循环的方式来更新，但是并不推荐使用，参考：

<update id="batchUpdateByForeach" parameterType="com.zyuan.boot.entity.EventOrder">
    <foreach collection="eventOrders" item="item" separator=";">
        update event_order
        set `event_name` = #{item.eventName},
            `event_type` = #{item.eventType},
            `order_no` = #{item.orderNo}
        where `id` = #{item.id}
    </foreach>
</update>

因为集合有多少数据，就执行多少次update，并不高效

使用Map操作

<update id="batchUpdateByMap" parameterType="java.util.Map">
    update event_order
    <trim prefix="set" suffixOverrides=",">
        <trim prefix="event_name = case" suffix="end,">
            <foreach collection="eventOrderMap.entrySet()" item="value" index="key">
                when `id` = #{key} then #{value.eventName}
            </foreach>
        </trim>
        <trim prefix="event_type = case" suffix="end,">
            <foreach collection="eventOrderMap.entrySet()" item="value" index="key">
                when `id` = #{key} then #{value.eventType}
            </foreach>
        </trim>
        <trim prefix="order_no = case" suffix="end">
            <foreach collection="eventOrderMap.entrySet()" item="value" index="key">
                when `id` = #{key} then #{value.orderNo}
            </foreach>
        </trim>
    </trim>
    where id in
    <foreach collection="eventOrderMap.entrySet()" item="value" index="key" open="(" close=")" separator=",">
        #{key}
    </foreach>
</update>

解释：其实map的循环只需要利用entrySet即可，并且在< foreach >标签中，index其实代表的就是map中的key，而遍历entrySet,，他的每一个元素就是value，其他的写法就与上面的批量更新一致。

测试：

@Test
public void batchUpdateByMap() {
    // key为id，value为对象
    Map<Long,EventOrder> eventOrderMap = getUpdateMap();
    eventOrderMapper.batchUpdateByMap(eventOrderMap);
}
​
private Map<Long,EventOrder> getUpdateMap() {
    Map<Long,EventOrder> eventOrderMap = new HashMap<>();
    for (Long i = 1L; i <= 10; i++) {
        EventOrder addEntity = new EventOrder();
        addEntity.setId(i);
        addEntity.setEventName(i + "事件");
        addEntity.setEventType(11);
        addEntity.setOrderNo("20.21");
        eventOrderMap.put(i,addEntity);
    }
    return eventOrderMap;
}

打印SQL：

UPDATE event_order 
SET event_name =
CASE
        WHEN `id` = ? THEN
        ? 
        WHEN `id` = ? THEN
        ? 
        WHEN `id` = ? THEN
        ? 
        WHEN `id` = ? THEN
        ? 
    END,
    event_type =
CASE
        WHEN `id` = ? THEN
        ? 
        WHEN `id` = ? THEN
        ? 
        WHEN `id` = ? THEN
        ? 
        WHEN `id` = ? THEN
        ? 
    END,
    order_no =
CASE
        WHEN `id` = ? THEN
        ? 
        WHEN `id` = ? THEN
        ? 
        WHEN `id` = ? THEN
        ? 
        WHEN `id` = ? THEN
        ? 
    END 
WHERE
    id IN ( ?, ?, ?, ? )