Q&A for participants in team and individual sport activities
with secs_table as (select datediff(second, t1.CreationDate, t2.CreationDate) as secs from Posts t1 inner join Posts t2 on t1.AcceptedAnswerId = t2.id where year(t1.CreationDate) = 2017) select avg(cast(secs as bigint)) from secs_table