SQL-Leetcode/1148-ArticleViews1.sql at main · ninad-moree/SQL-Leetcode · GitHub

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/*
    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.

    Example 1:

    Input:
    Views table:
    +------------+-----------+-----------+------------+
    | article_id | author_id | viewer_id | view_date  |
    +------------+-----------+-----------+------------+
    | 1          | 3         | 5         | 2019-08-01 |
    | 1          | 3         | 6         | 2019-08-02 |
    | 2          | 7         | 7         | 2019-08-01 |
    | 2          | 7         | 6         | 2019-08-02 |
    | 4          | 7         | 1         | 2019-07-22 |
    | 3          | 4         | 4         | 2019-07-21 |
    | 3          | 4         | 4         | 2019-07-21 |
    +------------+-----------+-----------+------------+
    Output:
    +------+
    | id   |
    +------+
    | 4    |
    | 7    |
    +------+
*/

SELECT distinct(author_id)  AS id
FROM Views
WHERE author_id = viewer_id
ORDER BY author_id ASC