ROW_NUMBER() was first introduced with window functions in
MariaDB 10.2.0.
 
Syntax
------ 
ROW_NUMBER() OVER (
 [ PARTITION BY partition_expression ]
 [ ORDER BY order_list ]
) 
 
Description
----------- 
ROW_NUMBER() is a window function that displays the number
of a given row, starting at one and following the ORDER BY
sequence of the window function, with identical values
receiving different row numbers. It is similar to the RANK()
and DENSE_RANK() functions except that in that function,
identical values will receive the same rank for each result.
 
Examples
-------- 
The distinction between DENSE_RANK(), RANK() and
ROW_NUMBER():
 
CREATE TABLE student(course VARCHAR(10), mark int, name
varchar(10));
 
INSERT INTO student VALUES 
 ('Maths', 60, 'Thulile'),
 ('Maths', 60, 'Pritha'),
 ('Maths', 70, 'Voitto'),
 ('Maths', 55, 'Chun'),
 ('Biology', 60, 'Bilal'),
 ('Biology', 70, 'Roger');
 
SELECT 
 RANK() OVER (PARTITION BY course ORDER BY mark DESC) AS
rank, 
 DENSE_RANK() OVER (PARTITION BY course ORDER BY mark DESC)
AS dense_rank, 
 ROW_NUMBER() OVER (PARTITION BY course ORDER BY mark DESC)
AS row_num, 
 course, mark, name 
FROM student ORDER BY course, mark DESC;
 
+------+------------+---------+---------+------+---------+
| rank | dense_rank | row_num | course | mark | name |
+------+------------+---------+---------+------+---------+
| 1 | 1 | 1 | Biology | 70 | Roger |
| 2 | 2 | 2 | Biology | 60 | Bilal |
| 1 | 1 | 1 | Maths | 70 | Voitto |
| 2 | 2 | 2 | Maths | 60 | Thulile |
| 2 | 2 | 3 | Maths | 60 | Pritha |
| 4 | 3 | 4 | Maths | 55 | Chun |
+------+------------+---------+---------+------+---------+
 


URL: https://mariadb.com/kb/en/row_number/