MEDIAN(median expression) OVER (
[ PARTITION BY partition_expression ]
)
Description
MEDIAN() is a window function that returns the median value of a range of values.
It is a specific case of PERCENTILE_CONT, with an argument of 0.5 and the ORDER BY column the one in MEDIAN's argument.
MEDIAN(<median-arg>) OVER ( [ PARTITION BY partition_expression] )
Is equivalent to:
PERCENTILE_CONT(0.5) WITHIN
GROUP (ORDER BY <median-arg>) OVER ( [ PARTITION BY partition_expression ])
Examples
CREATE TABLE book_rating (name CHAR(30), star_rating TINYINT);
INSERT INTO book_rating VALUES ('Lord of the Ladybirds', 5);
INSERT INTO book_rating VALUES ('Lord of the Ladybirds', 3);
INSERT INTO book_rating VALUES ('Lady of the Flies', 1);
INSERT INTO book_rating VALUES ('Lady of the Flies', 2);
INSERT INTO book_rating VALUES ('Lady of the Flies', 5);
SELECT name, median(star_rating) OVER (PARTITION BY name) FROM book_rating;
+-----------------------+----------------------------------------------+
| name | median(star_rating) OVER (PARTITION BY name) |
+-----------------------+----------------------------------------------+
| Lord of the Ladybirds | 4.0000000000 |
| Lord of the Ladybirds | 4.0000000000 |
| Lady of the Flies | 2.0000000000 |
| Lady of the Flies | 2.0000000000 |
| Lady of the Flies | 2.0000000000 |
+-----------------------+----------------------------------------------+
