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# 2346. Compute the Rank as a Percentage

## Description

Table: `Students`

+---------------+------+ | Column Name | Type | +---------------+------+ | student_id | int | | department_id | int | | mark | int | +---------------+------+ student_id is the primary key of this table. Each row of this table indicates a student's ID, the ID of the department in which the student enrolled, and their mark in the exam.

Write an SQL query that reports the rank of each student in their department as a percentage, where the rank as a percentage is computed using the following formula: `(student_rank_in_the_department - 1) * 100 / (the_number_of_students_in_the_department - 1)`

. The `percentage`

should be **rounded to 2 decimal places**. `student_rank_in_the_department`

is determined by **descending**** **`mark`

, such that the student with the highest `mark`

is `rank 1`

. If two students get the same mark, they also get the same rank.

Return the result table in **any order**.

The query result format is in the following example.

**Example 1:**

Input:Students table: +------------+---------------+------+ | student_id | department_id | mark | +------------+---------------+------+ | 2 | 2 | 650 | | 8 | 2 | 650 | | 7 | 1 | 920 | | 1 | 1 | 610 | | 3 | 1 | 530 | +------------+---------------+------+Output:+------------+---------------+------------+ | student_id | department_id | percentage | +------------+---------------+------------+ | 7 | 1 | 0.0 | | 1 | 1 | 50.0 | | 3 | 1 | 100.0 | | 2 | 2 | 0.0 | | 8 | 2 | 0.0 | +------------+---------------+------------+Explanation:For Department 1: - Student 7: percentage = (1 - 1) * 100 / (3 - 1) = 0.0 - Student 1: percentage = (2 - 1) * 100 / (3 - 1) = 50.0 - Student 3: percentage = (3 - 1) * 100 / (3 - 1) = 100.0 For Department 2: - Student 2: percentage = (1 - 1) * 100 / (2 - 1) = 0.0 - Student 8: percentage = (1 - 1) * 100 / (2 - 1) = 0.0