mirror of
https://gitee.com/coder-xiaomo/leetcode-problemset
synced 2025-11-04 03:33:12 +08:00
50 lines
1.5 KiB
HTML
50 lines
1.5 KiB
HTML
<p>Table: <code>Views</code></p>
|
|
|
|
<pre>
|
|
+---------------+---------+
|
|
| Column Name | Type |
|
|
+---------------+---------+
|
|
| article_id | int |
|
|
| author_id | int |
|
|
| viewer_id | int |
|
|
| view_date | date |
|
|
+---------------+---------+
|
|
There is no primary key for this table, it 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>
|
|
|
|
<p> </p>
|
|
|
|
<p>Write an SQL query to find all the authors that viewed at least one of their own articles.</p>
|
|
|
|
<p>Return the result table sorted by <code>id</code> in ascending order.</p>
|
|
|
|
<p>The query result format is in the following example.</p>
|
|
|
|
<p> </p>
|
|
<p><strong>Example 1:</strong></p>
|
|
|
|
<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>
|