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?     ### 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>
102 lines
3.9 KiB
Markdown
102 lines
3.9 KiB
Markdown
---
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layout: global
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title: PIVOT Clause
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displayTitle: PIVOT Clause
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license: |
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for additional information regarding copyright ownership.
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The ASF licenses this file to You under the Apache License, Version 2.0
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(the "License"); you may not use this file except in compliance with
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the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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---
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### Description
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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.
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### Syntax
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```sql
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PIVOT ( { aggregate_expression [ AS aggregate_expression_alias ] } [ , ... ]
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FOR column_list IN ( expression_list ) )
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```
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### Parameters
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* **aggregate_expression**
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Specifies an aggregate expression (SUM(a), COUNT(DISTINCT b), etc.).
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* **aggregate_expression_alias**
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Specifies an alias for the aggregate expression.
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* **column_list**
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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)`.
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* **expression_list**
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Specifies new columns, which are used to match values in `column_list` as the aggregating condition. We can also add aliases for them.
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### Examples
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```sql
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CREATE TABLE person (id INT, name STRING, age INT, class INT, address STRING);
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INSERT INTO person VALUES
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(100, 'John', 30, 1, 'Street 1'),
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(200, 'Mary', NULL, 1, 'Street 2'),
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(300, 'Mike', 80, 3, 'Street 3'),
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(400, 'Dan', 50, 4, 'Street 4');
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SELECT * FROM person
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PIVOT (
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SUM(age) AS a, AVG(class) AS c
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FOR name IN ('John' AS john, 'Mike' AS mike)
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);
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+------+-----------+---------+---------+---------+---------+
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| id | address | john_a | john_c | mike_a | mike_c |
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+------+-----------+---------+---------+---------+---------+
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| 200 | Street 2 | NULL | NULL | NULL | NULL |
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| 100 | Street 1 | 30 | 1.0 | NULL | NULL |
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| 300 | Street 3 | NULL | NULL | 80 | 3.0 |
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| 400 | Street 4 | NULL | NULL | NULL | NULL |
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+------+-----------+---------+---------+---------+---------+
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SELECT * FROM person
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PIVOT (
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SUM(age) AS a, AVG(class) AS c
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FOR (name, age) IN (('John', 30) AS c1, ('Mike', 40) AS c2)
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);
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+------+-----------+-------+-------+-------+-------+
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| id | address | c1_a | c1_c | c2_a | c2_c |
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+------+-----------+-------+-------+-------+-------+
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| 200 | Street 2 | NULL | NULL | NULL | NULL |
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| 100 | Street 1 | 30 | 1.0 | NULL | NULL |
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| 300 | Street 3 | NULL | NULL | NULL | NULL |
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| 400 | Street 4 | NULL | NULL | NULL | NULL |
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+------+-----------+-------+-------+-------+-------+
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```
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### Related Statements
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* [SELECT Main](sql-ref-syntax-qry-select.html)
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* [WHERE Clause](sql-ref-syntax-qry-select-where.html)
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* [GROUP BY Clause](sql-ref-syntax-qry-select-groupby.html)
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* [HAVING Clause](sql-ref-syntax-qry-select-having.html)
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* [ORDER BY Clause](sql-ref-syntax-qry-select-orderby.html)
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* [SORT BY Clause](sql-ref-syntax-qry-select-sortby.html)
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* [DISTRIBUTE BY Clause](sql-ref-syntax-qry-select-distribute-by.html)
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* [LIMIT Clause](sql-ref-syntax-qry-select-limit.html)
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* [CASE Clause](sql-ref-syntax-qry-select-case.html)
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* [LATERAL VIEW Clause](sql-ref-syntax-qry-select-lateral-view.html)
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