126 lines
5 KiB
Markdown
126 lines
5 KiB
Markdown
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---
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layout: global
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title: LATERAL VIEW Clause
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displayTitle: LATERAL VIEW 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 `LATERAL VIEW` clause is used in conjunction with generator functions such as `EXPLODE`, which will generate a virtual table containing one or more rows. `LATERAL VIEW` will apply the rows to each original output row.
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### Syntax
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```sql
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LATERAL VIEW [ OUTER ] generator_function ( expression [ , ... ] ) [ table_alias ] AS column_alias [ , ... ]
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```
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### Parameters
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* **OUTER**
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If `OUTER` specified, returns null if an input array/map is empty or null.
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* **generator_function**
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Specifies a generator function (EXPLODE, INLINE, etc.).
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* **table_alias**
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The alias for `generator_function`, which is optional.
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* **column_alias**
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Lists the column aliases of `generator_function`, which may be used in output rows. We may have multiple aliases if `generator_function` have multiple output columns.
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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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LATERAL VIEW EXPLODE(ARRAY(30, 60)) tabelName AS c_age
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LATERAL VIEW EXPLODE(ARRAY(40, 80)) AS d_age;
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+------+-------+-------+--------+-----------+--------+--------+
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| id | name | age | class | address | c_age | d_age |
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+------+-------+-------+--------+-----------+--------+--------+
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| 100 | John | 30 | 1 | Street 1 | 30 | 40 |
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| 100 | John | 30 | 1 | Street 1 | 30 | 80 |
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| 100 | John | 30 | 1 | Street 1 | 60 | 40 |
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| 100 | John | 30 | 1 | Street 1 | 60 | 80 |
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| 200 | Mary | NULL | 1 | Street 2 | 30 | 40 |
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| 200 | Mary | NULL | 1 | Street 2 | 30 | 80 |
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| 200 | Mary | NULL | 1 | Street 2 | 60 | 40 |
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| 200 | Mary | NULL | 1 | Street 2 | 60 | 80 |
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| 300 | Mike | 80 | 3 | Street 3 | 30 | 40 |
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| 300 | Mike | 80 | 3 | Street 3 | 30 | 80 |
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| 300 | Mike | 80 | 3 | Street 3 | 60 | 40 |
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| 300 | Mike | 80 | 3 | Street 3 | 60 | 80 |
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| 400 | Dan | 50 | 4 | Street 4 | 30 | 40 |
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| 400 | Dan | 50 | 4 | Street 4 | 30 | 80 |
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| 400 | Dan | 50 | 4 | Street 4 | 60 | 40 |
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| 400 | Dan | 50 | 4 | Street 4 | 60 | 80 |
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+------+-------+-------+--------+-----------+--------+--------+
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SELECT c_age, COUNT(1) FROM person
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LATERAL VIEW EXPLODE(ARRAY(30, 60)) AS c_age
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LATERAL VIEW EXPLODE(ARRAY(40, 80)) AS d_age
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GROUP BY c_age;
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+--------+-----------+
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| c_age | count(1) |
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+--------+-----------+
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| 60 | 8 |
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| 30 | 8 |
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+--------+-----------+
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SELECT * FROM person
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LATERAL VIEW EXPLODE(ARRAY()) tabelName AS c_age;
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+-----+-------+------+--------+----------+--------+
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| id | name | age | class | address | c_age |
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+-----+-------+------+--------+----------+--------+
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+-----+-------+------+--------+----------+--------+
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SELECT * FROM person
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LATERAL VIEW OUTER EXPLODE(ARRAY()) tabelName AS c_age;
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+------+-------+-------+--------+-----------+--------+
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| id | name | age | class | address | c_age |
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+------+-------+-------+--------+-----------+--------+
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| 100 | John | 30 | 1 | Street 1 | NULL |
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| 200 | Mary | NULL | 1 | Street 2 | NULL |
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| 300 | Mike | 80 | 3 | Street 3 | NULL |
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| 400 | Dan | 50 | 4 | Street 4 | 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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* [PIVOT Clause](sql-ref-syntax-qry-select-pivot.html)
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