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sql-ref-syntax-qry-select-orderby.md

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ORDER BY Clause
ORDER BY Clause
Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

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_oder ] [ , ... ] }

Parameters

  • ORDER BY

    Specifies a comma-separated list of expressions along with optional parameters sort_direction and nulls_sort_order which 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 ASC for ascending and DESC for 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_order is not specified, then NULLs sort first if sort order is ASC and NULLS sort last if sort order is DESC.

    1. If NULLS FIRST is specified, then NULL values are returned first regardless of the sort order.
    2. If NULLS LAST is specified, then NULL values are returned last regardless of the sort order.

    Syntax: [ NULLS { FIRST | LAST } ]

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|
+---+-----+----+

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