Leetcode SQL 50 -- 1148. Article Views I

LeetCode > SQL_50 SQL

Created At : 2024-10-24 11:12

Count:183 Views :

Question
1. Table name: Views
Explaination
1. SQL ORDER BY
Solution

Question

Table name: `Views`

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.

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.

Explaination

We have two tasks:

Authors viewed their own articles → WHERE author_id = viewer_id
Sort table by id in ascending order → ORDER BY author_id ASC

SQL ORDER BY

ORDER BY <column1>, <column2>, ... ASC|DESC;

By default, ORDER BY sort rows in ascending order.

And if there are multiple columns, sort the rows according to the first column, and then the second column when the rows contain same values in the first column and so on.

Solution

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