ARRAY_POPFRONT

array_popfront

SinceVersion 2.0.0

Description

Removes the first element from an array. The function returns a new array containing all elements from the original array except the first one.

Syntax

array_popfront(ARRAY<T> arr)

Parameters

• arr：ARRAY type, the array from which to remove the first element

Supported types for T:

• Numeric types: TINYINT, SMALLINT, INT, BIGINT, LARGEINT, FLOAT, DOUBLE, DECIMAL
• String types: CHAR, VARCHAR, STRING
• Date and time types: DATE, DATETIME, DATEV2, DATETIMEV2
• Boolean type: BOOLEAN
• IP types: IPV4, IPV6
• Complex types: ARRAY, MAP, STRUCT

Return Value

Return type: ARRAY

Return value meaning:

• Returns a new array containing all elements from the original array except the first one
• NULL: if the input array is NULL

Usage notes:

• The function removes the first element from the array and returns the remaining elements
• Empty arrays return empty arrays, arrays with only one element return empty arrays
• For null values in array elements: null elements are handled normally

Query Examples:

Remove the first element from a string array:

SELECT array_popfront(['apple', 'banana', 'cherry', 'date']);
+----------------------------------------------------+
| array_popfront(['apple', 'banana', 'cherry', 'date']) |
+----------------------------------------------------+
| ["banana", "cherry", "date"]                       |
+----------------------------------------------------+

Remove the first element from an array containing null values:

SELECT array_popfront([1, null, 3, null, 5]);
+------------------------------------------+
| array_popfront([1, null, 3, null, 5])   |
+------------------------------------------+
| [null, 3, null, 5]                      |
+------------------------------------------+

Arrays with only one element return empty arrays:

SELECT array_popfront([42]);
+------------------------+
| array_popfront([42])   |
+------------------------+
| []                     |
+------------------------+

Empty arrays return empty arrays:

SELECT array_popfront([]);
+------------------------+
| array_popfront([])     |
+------------------------+
| []                     |
+------------------------+

NULL arrays return NULL:

SELECT array_popfront(NULL);
+------------------------+
| array_popfront(NULL)   |
+------------------------+
| NULL                   |
+------------------------+

Remove the first element from an IP address array:

SELECT array_popfront(CAST(['192.168.1.1', '192.168.1.2', '192.168.1.3'] AS ARRAY<IPV4>));
+----------------------------------------------------------------------------------+
| array_popfront(CAST(['192.168.1.1', '192.168.1.2', '192.168.1.3'] AS ARRAY<IPV4>)) |
+----------------------------------------------------------------------------------+
| ["192.168.1.2", "192.168.1.3"]                                                   |
+----------------------------------------------------------------------------------+

Remove the first element from a nested array:

SELECT array_popfront([[1, 2], [3, 4], [5, 6]]);
+------------------------------------------+
| array_popfront([[1, 2], [3, 4], [5, 6]]) |
+------------------------------------------+
| [[3, 4], [5, 6]]                         |
+------------------------------------------+

Remove the first element from a MAP array:

SELECT array_popfront([{'name':'Alice','age':20}, {'name':'Bob','age':30}, {'name':'Charlie','age':40}]);
+------------------------------------------------------------------------------------------+
| array_popfront([{'name':'Alice','age':20}, {'name':'Bob','age':30}, {'name':'Charlie','age':40}]) |
+------------------------------------------------------------------------------------------+
| [{"name":"Bob","age":30}, {"name":"Charlie","age":40}]                                   |
+------------------------------------------------------------------------------------------+

Remove the first element from a STRUCT array:

SELECT array_popfront(array(named_struct('name','Alice','age',20), named_struct('name','Bob','age',30), named_struct('name','Charlie','age',40)));
+-------------------------------------------------------------------------------------------------------------------------------------------+
| array_popfront(array(named_struct('name','Alice','age',20), named_struct('name','Bob','age',30), named_struct('name','Charlie','age',40))) |
+-------------------------------------------------------------------------------------------------------------------------------------------+
| [{"name":"Bob", "age":30}, {"name":"Charlie", "age":40}]                                                                                  |
+-------------------------------------------------------------------------------------------------------------------------------------------+

Keywords

ARRAY, POPFRONT, ARRAY_POPFRONT