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+<h2><a href="https://leetcode.com/problems/percentage-of-users-attended-a-contest/">1633. Percentage of Users Attended a Contest</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>Users</code></p>
+
+<pre>+-------------+---------+
+| Column Name | Type    |
++-------------+---------+
+| user_id     | int     |
+| user_name   | varchar |
++-------------+---------+
+user_id is the primary key (column with unique values) for this table.
+Each row of this table contains the name and the id of a user.
+</pre>
+
+<p>&nbsp;</p>
+
+<p>Table: <code>Register</code></p>
+
+<pre>+-------------+---------+
+| Column Name | Type    |
++-------------+---------+
+| contest_id  | int     |
+| user_id     | int     |
++-------------+---------+
+(contest_id, user_id) is the primary key (combination of columns with unique values) for this table.
+Each row of this table contains the id of a user and the contest they registered into.
+</pre>
+
+<p>&nbsp;</p>
+
+<p>Write a solution to find the percentage of the users registered in each contest rounded to <strong>two decimals</strong>.</p>
+
+<p>Return the result table ordered by <code>percentage</code> in <strong>descending order</strong>. In case of a tie, order it by <code>contest_id</code> in <strong>ascending order</strong>.</p>
+
+<p>The result format is in the following example.</p>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+
+<pre><strong>Input:</strong> 
+Users table:
++---------+-----------+
+| user_id | user_name |
++---------+-----------+
+| 6       | Alice     |
+| 2       | Bob       |
+| 7       | Alex      |
++---------+-----------+
+Register table:
++------------+---------+
+| contest_id | user_id |
++------------+---------+
+| 215        | 6       |
+| 209        | 2       |
+| 208        | 2       |
+| 210        | 6       |
+| 208        | 6       |
+| 209        | 7       |
+| 209        | 6       |
+| 215        | 7       |
+| 208        | 7       |
+| 210        | 2       |
+| 207        | 2       |
+| 210        | 7       |
++------------+---------+
+<strong>Output:</strong> 
++------------+------------+
+| contest_id | percentage |
++------------+------------+
+| 208        | 100.0      |
+| 209        | 100.0      |
+| 210        | 100.0      |
+| 215        | 66.67      |
+| 207        | 33.33      |
++------------+------------+
+<strong>Explanation:</strong> 
+All the users registered in contests 208, 209, and 210. The percentage is 100% and we sort them in the answer table by contest_id in ascending order.
+Alice and Alex registered in contest 215 and the percentage is ((2/3) * 100) = 66.67%
+Bob registered in contest 207 and the percentage is ((1/3) * 100) = 33.33%
+</pre>
+</div>