(SQL Analytics 的 ORDER BY 子句) ORDER BY clause (SQL Analytics)

返回按用户指定顺序排序的结果行。Returns the result rows in a sorted manner in the user specified order. SORT BY 子句不同,此子句可保证输出的总序。Unlike the SORT BY clause, this clause guarantees a total order in the output.

语法Syntax

ORDER BY { expression [ sort_direction | nulls_sort_oder ] [ , ... ] }

参数Parameters

  • ORDER BYORDER BY

    用逗号分隔的表达式列表以及可选参数 sort_directionnulls_sort_order(用于对行进行排序)。A comma-separated list of expressions along with optional parameters sort_direction and nulls_sort_order which are used to sort the rows.

  • sort_directionsort_direction

    可选择指定是按升序还是降序对行进行排序。Optionally specifies whether to sort the rows in ascending or descending order. 排序方向的有效值为 ASC(升序)和 DESC(降序)。The valid values for the sort direction are ASC for ascending and DESC for descending. 如果未显式指定排序方向,则默认按升序对行排序。If sort direction is not explicitly specified, then by default rows are sorted ascending.

    语法: [ ASC | DESC ]Syntax: [ ASC | DESC ]

  • nulls_sort_ordernulls_sort_order

    可选择指定是在非 NULL 值之前还是之后返回 NULL 值。Optionally specifies whether NULL values are returned before/after non-NULL values. 如果未指定 null_sort_order,则在排序顺序为 ASC 时,Null 排在前面;排序顺序为 DESC 时,Null 排在后面。If null_sort_order is not specified, then NULLs sort first if sort order is ASC and NULLS sort last if sort order is DESC.

    1. 如果指定了 NULLS FIRST,则首先返回 NULL 值,而不考虑排序顺序。If NULLS FIRST is specified, then NULL values are returned first regardless of the sort order.
    2. 如果指定了 NULLS LAST,则最后返回 NULL 值,而不考虑排序顺序。If NULLS LAST is specified, then NULL values are returned last regardless of the sort order.

    语法: [ NULLS { FIRST | LAST } ]Syntax: [ NULLS { FIRST | LAST } ]

示例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|
+---+-----+----+