Practice Article Views I
Read the task, work through the examples, and check your approach against the constraints. Use the original LeetCode task for coding and submissions.
Problem Statement
Tables: Views(article_id INT, author_id INT, viewer_id INT, view_date DATE). Views permits duplicate rows. Equal author_id and viewer_id identify the same person. Return each author who viewed at least one of their own articles, once, under the column id. Sort id ascending.
Source: Article Views I on LeetCode. Use the original task for its coding environment and submissions.
Examples
# 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 | +------+
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