MySQL RANK() Function
The MySQL RANK()
function returns the rank within the partition in which the current row is located, starting at 1, with gaps.
That is, the same value has the same rank, but the rank of the next different value is row_number()
. For example, if there are 2 first places, then the rank of third place is 3
. This is different from the dense_rank()
function.
RANK()
Syntax
Here is the syntax of the MySQL RANK()
function:
RANK()
OVER (
[PARTITION BY partition_column_list]
[ORDER BY order_column_list]
)
Parameters
partition_column_list
-
List of columns for partitioning.
partition_column_list
-
List of columns for sorting.
Return value
The MySQL RANK()
function returns the rank within the partition in which the current row is located, starting at 1, with gaps.
RANK()
Examples
Preparing Data
Use the following CREATE TABLE
statement to create a table named student_grade
to store grades of students:
CREATE TABLE student_grade (
id INT AUTO_INCREMENT PRIMARY KEY,
name VARCHAR(50) NOT NULL,
class CHAR(1) NOT NULL,
subject VARCHAR(20) NOT NULL,
grade INT NOT NULL
);
This student_grade
table has 5 columns as following:
id
- The row ID, primary key.name
- The name of a student.class
- The class a student is in.subject
- The name of a subject.grade
- The grades for a subject and a student.
Insert some rows into the student_grade
table using the following INSERT
statement:
INSERT INTO student_grade
(name, class, subject, grade)
VALUES
('Tim', 'A', 'Math', 9),
('Tom', 'A', 'Math', 7),
('Jim', 'A', 'Math', 8),
('Tim', 'A', 'English', 7),
('Tom', 'A', 'English', 8),
('Jim', 'A', 'English', 7),
('Lucy', 'B', 'Math', 8),
('Jody', 'B', 'Math', 6),
('Susy', 'B', 'Math', 9),
('Lucy', 'B', 'English', 6),
('Jody', 'B', 'English', 7),
('Susy', 'B', 'English', 8);
Use the following SELECT
statement to show all rows in this table:
SELECT * FROM student_grade;
+----+------+-------+---------+-------+
| id | name | class | subject | grade |
+----+------+-------+---------+-------+
| 1 | Tim | A | Math | 9 |
| 2 | Tom | A | Math | 7 |
| 3 | Jim | A | Math | 8 |
| 4 | Tim | A | English | 7 |
| 5 | Tom | A | English | 8 |
| 6 | Jim | A | English | 7 |
| 7 | Lucy | B | Math | 8 |
| 8 | Jody | B | Math | 6 |
| 9 | Susy | B | Math | 9 |
| 10 | Lucy | B | English | 6 |
| 11 | Jody | B | English | 7 |
| 12 | Susy | B | English | 8 |
+----+------+-------+---------+-------+
12 rows in set (0.00 sec)
Example 1
To show the rank of each student in each subject in descending order of grade, use the following statement:
SELECT *,
RANK() OVER (
PARTITION BY subject
ORDER BY grade DESC
) "rank",
dense_rank() OVER (
PARTITION BY subject
ORDER BY grade DESC
) "dense_rank"
FROM student_grade;
+----+------+-------+---------+-------+------+------------+
| id | name | class | subject | grade | RANK | dense_rank |
+----+------+-------+---------+-------+------+------------+
| 5 | Tom | A | English | 8 | 1 | 1 |
| 12 | Susy | B | English | 8 | 1 | 1 |
| 4 | Tim | A | English | 7 | 3 | 2 |
| 6 | Jim | A | English | 7 | 3 | 2 |
| 11 | Jody | B | English | 7 | 3 | 2 |
| 10 | Lucy | B | English | 6 | 6 | 3 |
| 1 | Tim | A | Math | 9 | 1 | 1 |
| 9 | Susy | B | Math | 9 | 1 | 1 |
| 3 | Jim | A | Math | 8 | 3 | 2 |
| 7 | Lucy | B | Math | 8 | 3 | 2 |
| 2 | Tom | A | Math | 7 | 5 | 3 |
| 8 | Jody | B | Math | 6 | 6 | 4 |
+----+------+-------+---------+-------+------+------------+
12 rows in set (0.00 sec)
Note that the window function in the SQL statement above:
RANK() OVER (
PARTITION BY subject
ORDER BY grade DESC
)
In the OVER
clause,
- The
PARTITION BY subject
partitions all rows by subject - The
ORDER BY grade DESC
sorts all rows within each partition in descending order by grade. - The
RANK()
returns the rank of each row within its associated partition.
You can also see the difference between rank()
and dense_rank()
from above.
Example 2
To show the rank of each student in each class in descending order of total grade, use the following statement:
SELECT t.*,
RANK() OVER (
PARTITION BY class
ORDER BY t.sum_grade DESC
) "rank"
FROM (
SELECT class,
name,
sum(grade) sum_grade
FROM student_grade
GROUP BY class, name
) t;
+-------+------+-----------+------+
| class | name | sum_grade | RANK |
+-------+------+-----------+------+
| A | Tim | 16 | 1 |
| A | Tom | 15 | 2 |
| A | Jim | 15 | 2 |
| B | Susy | 17 | 1 |
| B | Lucy | 14 | 2 |
| B | Jody | 13 | 3 |
+-------+------+-----------+------+
6 rows in set (0.01 sec)
Notice this subquery in the above statement:
SELECT class,
name,
sum(grade) sum_grade
FROM student_grade
GROUP BY class, name
This subquery uses the GROUP BY
clause and the sum()
function sums up each student’s total grade by class and student.
+-------+------+-----------+
| class | name | sum_grade |
+-------+------+-----------+
| A | Tim | 16 |
| A | Tom | 15 |
| A | Jim | 15 |
| B | Lucy | 14 |
| B | Jody | 13 |
| B | Susy | 17 |
+-------+------+-----------+
6 rows in set (0.01 sec)
The main statement partitions all rows from this subquery by classes, then sort by total grade in descending order within each partition, and gets the rank of each row within its associated partition using RANK()
.