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Mybatis?批量更新實(shí)體對(duì)象方式

更新時(shí)間：2021年11月26日 11:19:06 作者：zyqok

這篇文章主要介紹了Mybatis?批量更新實(shí)體對(duì)象方式，具有很好的參考價(jià)值，希望對(duì)大家有所幫助。如有錯(cuò)誤或未考慮完全的地方，望不吝賜教

Mybatis批量更新實(shí)體對(duì)象

（1）Dao層接口

    /**
     * 根據(jù)更新采購計(jì)劃（批量）
     * @param plans
     */
    void batchUpdatePlan(List<PubPurchasePlan> plans);

（2）Mapper.xml 文件

<sql id="batchUpdatePlanCondition">
    <where>
        <foreach collection="list" item="item" open="( " separator=") or (" close=" )">
            comId = #{item.comId} AND id = #{item.id}
        </foreach>
    </where>
</sql>
<update id="batchUpdatePlan" parameterType="list">
        UPDATE pub_purchase_plan
        <trim prefix="set" suffixOverrides=",">
            <trim prefix="warehouseId=case" suffix="end,">
                 <foreach collection="list" item="item" index="index">
                    WHEN comId = #{item.comId} AND id = #{item.id} THEN #{item.warehouseId}
                 </foreach>
            </trim>
            <trim prefix="productId=case" suffix="end,">
                 <foreach collection="list" item="item" index="index">
                   WHEN comId = #{item.comId} AND id = #{item.id} THEN #{item.productId}
                 </foreach>
            </trim>
            <trim prefix="amount=case" suffix="end,">
                 <foreach collection="list" item="item" index="index">
                   WHEN comId = #{item.comId} AND id = #{item.id} THEN #{item.amount}
                 </foreach>
            </trim>
            <trim prefix="deleted=case" suffix="end,">
                 <foreach collection="list" item="item" index="index">
                   WHEN comId = #{item.comId} AND id = #{item.id} THEN #{item.deleted}
                 </foreach>
            </trim>
            <trim prefix="price=case" suffix="end,">
                 <foreach collection="list" item="item" index="index">
                   WHEN comId = #{item.comId} AND id = #{item.id} THEN #{item.price}
                 </foreach>
            </trim>
            <trim prefix="type=case" suffix="end,">
                 <foreach collection="list" item="item" index="index">
                   WHEN comId = #{item.comId} AND id = #{item.id} THEN #{item.type}
                 </foreach>
            </trim>
        </trim>
        <include refid="batchUpdatePlanCondition"/>
</update>

Mybatis批量更新數(shù)據(jù)三種方法效率對(duì)比

探討批量更新數(shù)據(jù)三種寫法的效率問題

實(shí)現(xiàn)方式有三種

1、用for循環(huán)通過循環(huán)傳過來的參數(shù)集合，循環(huán)出N條sql
2、用mysql的case when 條件判斷變相的進(jìn)行批量更新
3、用ON DUPLICATE KEY UPDATE進(jìn)行批量更新

下面進(jìn)行實(shí)現(xiàn)。

注意第一種方法要想成功，需要在db鏈接url后面帶一個(gè)參數(shù) &allowMultiQueries=true

即： jdbc:mysql://localhost:3306/mysqlTest?characterEncoding=utf-8&allowMultiQueries=true

其實(shí)這種東西寫過來寫過去就是差不多一樣的代碼，不做重復(fù)的贅述，直接上代碼。

 
    <!-- 批量更新第一種方法，通過接收傳進(jìn)來的參數(shù)list進(jìn)行循環(huán)著組裝sql -->
     <update id="updateBatch" parameterType="java.util.List" >
        <foreach collection="list" item="item" index="index" open="" close="" separator=";">
            update standard_relation
            <set >
                <if test="item.standardFromUuid != null" >
                    standard_from_uuid = #{item.standardFromUuid,jdbcType=VARCHAR},
                </if>
                <if test="item.standardToUuid != null" >
                    standard_to_uuid = #{item.standardToUuid,jdbcType=VARCHAR},
                </if>
                <if test="item.gmtModified != null" >
                    gmt_modified = #{item.gmtModified,jdbcType=TIMESTAMP},
                </if>
            </set>
            where id = #{item.id,jdbcType=BIGINT}
        </foreach>
    </update>
 
    <!-- 批量更新第二種方法，通過 case when語句變相的進(jìn)行批量更新 -->
    <update id="updateBatch" parameterType="java.util.List" >
        update standard_relation
        <trim prefix="set" suffixOverrides=",">
            <trim prefix="standard_from_uuid =case" suffix="end,">
                <foreach collection="list" item="i" index="index">
                    <if test="i.standardFromUuid!=null">
                        when id=#{i.id} then #{i.standardFromUuid}
                    </if>
                </foreach>
            </trim>
            <trim prefix="standard_to_uuid =case" suffix="end,">
                <foreach collection="list" item="i" index="index">
                    <if test="i.standardToUuid!=null">
                        when id=#{i.id} then #{i.standardToUuid}
                    </if>
                </foreach>
            </trim>
            <trim prefix="gmt_modified =case" suffix="end,">
                <foreach collection="list" item="i" index="index">
                    <if test="i.gmtModified!=null">
                        when id=#{i.id} then #{i.gmtModified}
                    </if>
                </foreach>
            </trim>
        </trim>
        where
        <foreach collection="list" separator="or" item="i" index="index" >
            id=#{i.id}
        </foreach>
    </update>
批量更新第三種方法，用ON DUPLICATE KEY UPDATE
 <insert id="updateBatch" parameterType="java.util.List">
        insert into standard_relation(id,relation_type, standard_from_uuid,
        standard_to_uuid, relation_score, stat,
        last_process_id, is_deleted, gmt_created,
        gmt_modified,relation_desc)VALUES
        <foreach collection="list" item="item" index="index" separator=",">
            (#{item.id,jdbcType=BIGINT},#{item.relationType,jdbcType=VARCHAR}, #{item.standardFromUuid,jdbcType=VARCHAR},
            #{item.standardToUuid,jdbcType=VARCHAR}, #{item.relationScore,jdbcType=DECIMAL}, #{item.stat,jdbcType=TINYINT},
            #{item.lastProcessId,jdbcType=BIGINT}, #{item.isDeleted,jdbcType=TINYINT}, #{item.gmtCreated,jdbcType=TIMESTAMP},
            #{item.gmtModified,jdbcType=TIMESTAMP},#{item.relationDesc,jdbcType=VARCHAR})
        </foreach>
        ON DUPLICATE KEY UPDATE
        id=VALUES(id),relation_type = VALUES(relation_type),standard_from_uuid = VALUES(standard_from_uuid),standard_to_uuid = VALUES(standard_to_uuid),
        relation_score = VALUES(relation_score),stat = VALUES(stat),last_process_id = VALUES(last_process_id),
        is_deleted = VALUES(is_deleted),gmt_created = VALUES(gmt_created),
        gmt_modified = VALUES(gmt_modified),relation_desc = VALUES(relation_desc)
    </insert>

 @Override
    public void updateStandardRelations() {
        List<StandardRelation> list=standardRelationMapper.selectByStandardUuid("xiemingjieupdate");
        for(StandardRelation tmp:list){
            tmp.setStandardFromUuid(tmp.getStandardFromUuid()+"update");
            tmp.setStandardToUuid(tmp.getStandardToUuid()+"update");
        }
        long begin=System.currentTimeMillis();
        standardRelationManager.updateBatch(list);
        long end=System.currentTimeMillis();
        System.out.print("當(dāng)前的批量更新的方法用時(shí)"+(end-begin)+"ms");
    }

sql語句for循環(huán)效率其實(shí)相當(dāng)高的，因?yàn)樗鼉H僅有一個(gè)循環(huán)體，只不過最后update語句比較多，量大了就有可能造成sql阻塞。

case when雖然最后只會(huì)有一條更新語句，但是xml中的循環(huán)體有點(diǎn)多，每一個(gè)case when 都要循環(huán)一遍list集合，所以大批量拼sql的時(shí)候會(huì)比較慢，所以效率問題嚴(yán)重。使用的時(shí)候建議分批插入。

duplicate key update可以看出來是最快的，但是一般大公司都禁用，公司一般都禁止使用replace into和INSERT INTO … ON DUPLICATE KEY UPDATE，這種sql有可能會(huì)造成數(shù)據(jù)丟失和主從上表的自增id值不一致。而且用這個(gè)更新時(shí)，記得一定要加上id，而且values（）括號(hào)里面放的是數(shù)據(jù)庫字段，不是java對(duì)象的屬性字段。