Mybaties-puls 坑 - 技术栈

1、Mybaties-puls提供的所用的批量操作方法，其实底层是通过for循环遍历操作的每一条数据，只是在数据传输上执行了一次io，减少io的次数，并没有减少操作数据库的次数。

2、mapper中手写sql ，注意：在批量操作之前判断数组不为空

2.1批量插入

sql 复制代码

 <insert id="insertBatch" parameterType="java.util.List">
        insert into user(
        user_id,
        user_name,
        create_time,
        update_time
        )
        values
        <foreach collection="list" item="item" index="index" separator=",">
            (
            #{item.UserId},
            #{item.UserName},
            now(),
            now()
            )
        </foreach>
    </insert>

2.2 根据id批量更新

sql 复制代码

    <update id="batchUpdate" parameterType="java.util.List">
        update mg_cps_goods_rate_config
        <trim prefix="set" suffixOverrides=",">
            <trim prefix="user_id =case" suffix="end,">
                <foreach collection="list" item="item" index="index">
                    <if test="item.UserId!=null">
                        when id=#{item.id} then #{item.UserId}
                    </if>
                    <if test="item.UserId == null">
                        when id=#{item.id} then user.user_id
                    </if>
                </foreach>
            </trim>

            <trim prefix="user_name =case" suffix="end,">
                <foreach collection="list" item="item" index="index">
                    <if test="item.UserName!=null">
                        when id=#{item.id} then #{item.UserName}
                    </if>
                    <if test="item.updateUserName == null">
                        when id=#{item.id} then user.user_name
                    </if>
                </foreach>
            </trim>
            <trim prefix="update_time =case" suffix="end,">
                <foreach collection="list" item="item" index="index">
                    <if test="item.updateTime!=null">
                        when id=#{item.id} then #{item.updateTime}
                    </if>
                    <if test="item.updateTime == null">
                        when id=#{item.id} then user.update_time
                    </if>
                </foreach>
            </trim>
        </trim>
        where mark = 1
        and id in
        <foreach collection="list" item="item" index="index" separator="," open="(" close=")">
            #{item.id,jdbcType=BIGINT}
        </foreach>
    </update>

2.3 in 多字段为调价时，用insql

java 复制代码

  List<String> list = new ArrayList();
        for (int i = 0; i < 5; i++) {
            Good good = new Good();
            good.setType(0);
            good.setShopId(i+10L);
            good.setSkuId((long) i);
            list.add("(" + good.getSkuId() + "," + good.getShopId() +")");
        }
        System.out.println("asList" + list);
        //字符串数组转字符串
        String join = StringUtils.join(list.toArray(), ",");
        System.out.println("strings1" + join);
        QueryWrapper<Good> queryWrapper = new QueryWrapper<>();
        // default Children inSql(R column, String inValue)
        queryWrapper.inSql("(sku_id,shop_id)",join);
        return this.list(queryWrapper);