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<h2><a href="https://leetcode.com/problems/article-views-i/">1148. Article Views I</a></h2><h3>Easy</h3><hr><div class="sql-schema-wrapper__3VBi"><a class="sql-schema-link__3cEg">SQL Schema<svg viewBox="0 0 24 24" width="1em" height="1em" class="icon__1Md2"><path fill-rule="evenodd" d="M10 6L8.59 7.41 13.17 12l-4.58 4.59L10 18l6-6z"></path></svg></a></div><div><p>Table: <code>Views</code></p> | ||
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<pre>+---------------+---------+ | ||
| Column Name | Type | | ||
+---------------+---------+ | ||
| article_id | int | | ||
| author_id | int | | ||
| viewer_id | int | | ||
| view_date | date | | ||
+---------------+---------+ | ||
There is no primary key (column with unique values) for this table, the table may have duplicate rows. | ||
Each row of this table indicates that some viewer viewed an article (written by some author) on some date. | ||
Note that equal author_id and viewer_id indicate the same person. | ||
</pre> | ||
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<p> </p> | ||
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<p>Write a solution to find all the authors that viewed at least one of their own articles.</p> | ||
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<p>Return the result table sorted by <code>id</code> in ascending order.</p> | ||
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<p>The result format is in the following example.</p> | ||
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<p> </p> | ||
<p><strong class="example">Example 1:</strong></p> | ||
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<pre><strong>Input:</strong> | ||
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 | | ||
+------------+-----------+-----------+------------+ | ||
<strong>Output:</strong> | ||
+------+ | ||
| id | | ||
+------+ | ||
| 4 | | ||
| 7 | | ||
+------+ | ||
</pre> | ||
</div> |