spark-instrumented-optimizer/docs/sql-ref-syntax-qry-select-lateral-view.md

---
layout: global
title: LATERAL VIEW Clause
displayTitle: LATERAL VIEW Clause
license: |
  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
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  distributed under the License is distributed on an "AS IS" BASIS,
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---

### Description

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.

### Syntax

```sql
LATERAL VIEW [ OUTER ] generator_function ( expression [ , ... ] ) [ table_alias ] AS column_alias [ , ... ]
```

### Parameters

* **OUTER**

    If `OUTER` specified, returns null if an input array/map is empty or null. 
    
* **generator_function**

    Specifies a generator function (EXPLODE, INLINE, etc.).
    
* **table_alias**

    The alias for `generator_function`, which is optional.
     
* **column_alias**

    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.
         
### Examples

```sql
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
    LATERAL VIEW EXPLODE(ARRAY(30, 60)) tableName AS c_age
    LATERAL VIEW EXPLODE(ARRAY(40, 80)) AS d_age;
+------+-------+-------+--------+-----------+--------+--------+
|  id  | name  |  age  | class  |  address  | c_age  | d_age  |
+------+-------+-------+--------+-----------+--------+--------+
| 100  | John  | 30    | 1      | Street 1  | 30     | 40     |
| 100  | John  | 30    | 1      | Street 1  | 30     | 80     |
| 100  | John  | 30    | 1      | Street 1  | 60     | 40     |
| 100  | John  | 30    | 1      | Street 1  | 60     | 80     |
| 200  | Mary  | NULL  | 1      | Street 2  | 30     | 40     |
| 200  | Mary  | NULL  | 1      | Street 2  | 30     | 80     |
| 200  | Mary  | NULL  | 1      | Street 2  | 60     | 40     |
| 200  | Mary  | NULL  | 1      | Street 2  | 60     | 80     |
| 300  | Mike  | 80    | 3      | Street 3  | 30     | 40     |
| 300  | Mike  | 80    | 3      | Street 3  | 30     | 80     |
| 300  | Mike  | 80    | 3      | Street 3  | 60     | 40     |
| 300  | Mike  | 80    | 3      | Street 3  | 60     | 80     |
| 400  | Dan   | 50    | 4      | Street 4  | 30     | 40     |
| 400  | Dan   | 50    | 4      | Street 4  | 30     | 80     |
| 400  | Dan   | 50    | 4      | Street 4  | 60     | 40     |
| 400  | Dan   | 50    | 4      | Street 4  | 60     | 80     |
+------+-------+-------+--------+-----------+--------+--------+

SELECT c_age, COUNT(1) FROM person
    LATERAL VIEW EXPLODE(ARRAY(30, 60)) AS c_age
    LATERAL VIEW EXPLODE(ARRAY(40, 80)) AS d_age 
GROUP BY c_age;
+--------+-----------+
| c_age  | count(1)  |
+--------+-----------+
| 60     | 8         |
| 30     | 8         |
+--------+-----------+

SELECT * FROM person
    LATERAL VIEW EXPLODE(ARRAY()) tableName AS c_age;
+-----+-------+------+--------+----------+--------+
| id  | name  | age  | class  | address  | c_age  |
+-----+-------+------+--------+----------+--------+
+-----+-------+------+--------+----------+--------+

SELECT * FROM person
    LATERAL VIEW OUTER EXPLODE(ARRAY()) tableName AS c_age;
+------+-------+-------+--------+-----------+--------+
|  id  | name  |  age  | class  |  address  | c_age  |
+------+-------+-------+--------+-----------+--------+
| 100  | John  | 30    | 1      | Street 1  | NULL   |
| 200  | Mary  | NULL  | 1      | Street 2  | NULL   |
| 300  | Mike  | 80    | 3      | Street 3  | NULL   |
| 400  | Dan   | 50    | 4      | Street 4  | NULL   |
+------+-------+-------+--------+-----------+--------+
```

### Related Statements

* [SELECT Main](sql-ref-syntax-qry-select.html)
* [WHERE Clause](sql-ref-syntax-qry-select-where.html)
* [GROUP BY Clause](sql-ref-syntax-qry-select-groupby.html)
* [HAVING Clause](sql-ref-syntax-qry-select-having.html)
* [ORDER BY Clause](sql-ref-syntax-qry-select-orderby.html)
* [SORT BY Clause](sql-ref-syntax-qry-select-sortby.html)
* [DISTRIBUTE BY Clause](sql-ref-syntax-qry-select-distribute-by.html)
* [LIMIT Clause](sql-ref-syntax-qry-select-limit.html)
* [CASE Clause](sql-ref-syntax-qry-select-case.html)
* [PIVOT Clause](sql-ref-syntax-qry-select-pivot.html)