mysql avg（min（））可以做到吗？

Question

显然avg（min（））给我一个错误，所以我尝试了这个代码，但它给了我错误的数字。有什么想法吗？

由于

select
    out_year as "Year",
    avg(dwell_time) as "Average",
    avg(av.dw_min) as "Minimum",
    avg(av.dw_max) as "Maximum"
from
    (select min(dwell_time) as dw_min, max(dwell_time) as dw_max
    from eq_dwell) av,
    eq_dwell ed
where
    inv_status = "Offdock"
group by out_year