Unable to resolve table 'sys_role_user'

<?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="rbacmapper">
    <select id="selectNodeByUserId" parameterType="Long" resultType="com.imooc.oa.entity.Node">
        SELECT DISTINCT n.*
        FROM sys_role_user ru, sys_role_node rn, sys_node n
        WHERE
            user_id = #{value} AND ru.role_id = rn.role_id AND rn.node_id = n.node_id
        ORDER BY
            n.node_code
    </select>
</mapper>