8de43338be
### What changes were proposed in this pull request? update sql-ref docs, the following key words will be added in this PR. CASE/ELSE WHEN/THEN MAP KEYS TERMINATED BY NULL DEFINED AS LINES TERMINATED BY ESCAPED BY COLLECTION ITEMS TERMINATED BY PIVOT LATERAL VIEW OUTER? ROW FORMAT SERDE ROW FORMAT DELIMITED FIELDS TERMINATED BY IGNORE NULLS FIRST LAST ### Why are the changes needed? let more users know the sql key words usage ### Does this PR introduce _any_ user-facing change? ![image](https://user-images.githubusercontent.com/46367746/88148830-c6dc1f80-cc31-11ea-81ea-13bc9dc34550.png) ![image](https://user-images.githubusercontent.com/46367746/88148968-fb4fdb80-cc31-11ea-8649-e8297cf5813e.png) ![image](https://user-images.githubusercontent.com/46367746/88149000-073b9d80-cc32-11ea-9aa4-f914ecd72663.png) ![image](https://user-images.githubusercontent.com/46367746/88149021-0f93d880-cc32-11ea-86ed-7db8672b5aac.png) ### How was this patch tested? No Closes #29056 from GuoPhilipse/add-missing-keywords. Lead-authored-by: GuoPhilipse <guofei_ok@126.com> Co-authored-by: GuoPhilipse <46367746+GuoPhilipse@users.noreply.github.com> Signed-off-by: Takeshi Yamamuro <yamamuro@apache.org>
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layout | title | displayTitle | license |
---|---|---|---|
global | 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 |
+------+-----------+-------+-------+-------+-------+