Number of comments per pull request
select avg(num_comments), project_name, url
from
(
(select count(pull_request_comments.comment_id) as num_comments, projects.id as project_id, projects.name as project_name, projects.url as url, pull_requests.id as pull_request_id
from pull_request_comments
join pull_requests on pull_requests.id = pull_request_comments.pull_request_id
join projects on projects.id = pull_requests.base_repo_id
group by projects.id, pull_requests.id) comment_nums
)
group by project_id