src/main/resources/mapper/UserStatsMapper.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.example.g8backend.mapper.UserStatsMapper">
    <update id="incrementTraffic">
        UPDATE user_stats
        SET total_upload = total_upload + #{deltaUploaded},
            total_download = total_download + #{deltaDownloaded}
        WHERE passkey = #{passkey}
    </update>
</mapper>