多个平均数列的子查询

SELECT company_name, title, teachername, company.id,average
    FROM companies company
    left outer join (select ROUND(avg(score), 2) as average, company_id
       from companycomments
       group by company_id) companycomments
    on company.id = companycomments.company_id
    left outer join
    (
     select company_id, title,teachername
     from trainings, teachers, teachers_trainings
     where teachers.id = teachers_trainings.teacher_id
           and teachers_trainings.training_id = trainings.id
    ) totalInfo
    on company.id = totalInfo.company_id