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- -- 1148. Article Views I
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- --
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- -- Table: Views
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- --
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- -- +---------------+---------+
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- -- | Column Name | Type |
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- -- +---------------+---------+
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- -- | article_id | int |
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- -- | author_id | int |
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- -- | viewer_id | int |
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- -- | view_date | date |
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- -- +---------------+---------+
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- -- There is no primary key for this table, it may have duplicate rows.
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- -- Each row of this table indicates that some viewer viewed an article (written by some author) on some date.
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- -- Note that equal author_id and viewer_id indicate the same person.
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- --
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- --
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- -- Write an SQL query to find all the authors that viewed at least one of their own articles, sorted in ascending order by their id.
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- --
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- -- The query result format is in the following example:
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- --
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- -- Views table:
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- -- +------------+-----------+-----------+------------+
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- -- | article_id | author_id | viewer_id | view_date |
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- -- +------------+-----------+-----------+------------+
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- -- | 1 | 3 | 5 | 2019-08-01 |
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- -- | 1 | 3 | 6 | 2019-08-02 |
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- -- | 2 | 7 | 7 | 2019-08-01 |
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- -- | 2 | 7 | 6 | 2019-08-02 |
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- -- | 4 | 7 | 1 | 2019-07-22 |
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- -- | 3 | 4 | 4 | 2019-07-21 |
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- -- | 3 | 4 | 4 | 2019-07-21 |
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- -- +------------+-----------+-----------+------------+
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- --
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- -- Result table:
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- -- +------+
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- -- | id |
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- -- +------+
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- -- | 4 |
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- -- | 7 |
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- -- +------+
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-
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- -- # Write your MySQL query statement below
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select distinct (author_id) as id from Views where author_id = viewer_id order by id asc ;
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