ORDER BY Clause
Description
The ORDER BY clause is used to return the result rows in a sorted manner
in the user specified order. Unlike the SORT BY
clause, this clause guarantees a total order in the output.
Syntax
ORDER BY { expression [ sort_direction | nulls_sort_order ] [ , ... ] }
Parameters
-
ORDER BY
Specifies a comma-separated list of expressions along with optional parameters
sort_directionandnulls_sort_orderwhich are used to sort the rows. -
sort_direction
Optionally specifies whether to sort the rows in ascending or descending order. The valid values for the sort direction are
ASCfor ascending andDESCfor descending. If sort direction is not explicitly specified, then by default rows are sorted ascending.Syntax: [ ASC
|DESC ] -
nulls_sort_order
Optionally specifies whether NULL values are returned before/after non-NULL values. If
null_sort_orderis not specified, then NULLs sort first if sort order isASCand NULLS sort last if sort order isDESC.- If
NULLS FIRSTis specified, then NULL values are returned first regardless of the sort order. - If
NULLS LASTis specified, then NULL values are returned last regardless of the sort order.
Syntax:
[ NULLS { FIRST | LAST } ] - If
Examples
CREATE TABLE person (id INT, name STRING, age INT);
INSERT INTO person VALUES
(100, 'John', 30),
(200, 'Mary', NULL),
(300, 'Mike', 80),
(400, 'Jerry', NULL),
(500, 'Dan', 50);
-- Sort rows by age. By default rows are sorted in ascending manner with NULL FIRST.
SELECT name, age FROM person ORDER BY age;
+-----+----+
| name| age|
+-----+----+
|Jerry|null|
| Mary|null|
| John| 30|
| Dan| 50|
| Mike| 80|
+-----+----+
-- Sort rows in ascending manner keeping null values to be last.
SELECT name, age FROM person ORDER BY age NULLS LAST;
+-----+----+
| name| age|
+-----+----+
| John| 30|
| Dan| 50|
| Mike| 80|
| Mary|null|
|Jerry|null|
+-----+----+
-- Sort rows by age in descending manner, which defaults to NULL LAST.
SELECT name, age FROM person ORDER BY age DESC;
+-----+----+
| name| age|
+-----+----+
| Mike| 80|
| Dan| 50|
| John| 30|
|Jerry|null|
| Mary|null|
+-----+----+
-- Sort rows in ascending manner keeping null values to be first.
SELECT name, age FROM person ORDER BY age DESC NULLS FIRST;
+-----+----+
| name| age|
+-----+----+
|Jerry|null|
| Mary|null|
| Mike| 80|
| Dan| 50|
| John| 30|
+-----+----+
-- Sort rows based on more than one column with each column having different
-- sort direction.
SELECT * FROM person ORDER BY name ASC, age DESC;
+---+-----+----+
| id| name| age|
+---+-----+----+
|500| Dan| 50|
|400|Jerry|null|
|100| John| 30|
|200| Mary|null|
|300| Mike| 80|
+---+-----+----+