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

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PIVOT Clause
PIVOT 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 PIVOT clause is used for data perspective. We can get the aggregated values based on specific column values, which will be turned to multiple columns used in SELECT clause. The PIVOT clause can be specified after the table name or subquery.

Syntax

PIVOT ( { aggregate_expression [ AS aggregate_expression_alias ] } [ , ... ]
    FOR column_list IN ( expression_list ) )

Parameters

  • aggregate_expression

    Specifies an aggregate expression (SUM(a), COUNT(DISTINCT b), etc.).

  • aggregate_expression_alias

    Specifies an alias for the aggregate expression.

  • column_list

    Contains columns in the FROM clause, which specifies the columns we want to replace with new columns. We can use brackets to surround the columns, such as (c1, c2).

  • expression_list

    Specifies new columns, which are used to match values in column_list as the aggregating condition. We can also add aliases for them.

Examples

CREATE TABLE person (id INT, name STRING, age INT, class INT, address STRING);
INSERT INTO person VALUES
    (100, 'John', 30, 1, 'Street 1'),
    (200, 'Mary', NULL, 1, 'Street 2'),
    (300, 'Mike', 80, 3, 'Street 3'),
    (400, 'Dan', 50, 4, 'Street 4');

SELECT * FROM person
    PIVOT (
        SUM(age) AS a, AVG(class) AS c
        FOR name IN ('John' AS john, 'Mike' AS mike)
    );
+------+-----------+---------+---------+---------+---------+
|  id  |  address  | john_a  | john_c  | mike_a  | mike_c  |
+------+-----------+---------+---------+---------+---------+
| 200  | Street 2  | NULL    | NULL    | NULL    | NULL    |
| 100  | Street 1  | 30      | 1.0     | NULL    | NULL    |
| 300  | Street 3  | NULL    | NULL    | 80      | 3.0     |
| 400  | Street 4  | NULL    | NULL    | NULL    | NULL    |
+------+-----------+---------+---------+---------+---------+

SELECT * FROM person
    PIVOT (
        SUM(age) AS a, AVG(class) AS c
        FOR (name, age) IN (('John', 30) AS c1, ('Mike', 40) AS c2)
    );
+------+-----------+-------+-------+-------+-------+
|  id  |  address  | c1_a  | c1_c  | c2_a  | c2_c  |
+------+-----------+-------+-------+-------+-------+
| 200  | Street 2  | NULL  | NULL  | NULL  | NULL  |
| 100  | Street 1  | 30    | 1.0   | NULL  | NULL  |
| 300  | Street 3  | NULL  | NULL  | NULL  | NULL  |
| 400  | Street 4  | NULL  | NULL  | NULL  | NULL  |
+------+-----------+-------+-------+-------+-------+

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