[코드카타] SQL 19 Article Views I

[코드카타] SQL 19 Article Views I

19. Article Views I
https://leetcode.com/problems/article-views-i/

Write a solution to find all the authors that viewed 
at least one of their own articles.
Return the result table sorted by id in ascending order.

select author_id id
from views
where author_id = viewer_id
group by 1
order by 1

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