ARRAY_POPBACK

array_popback

SinceVersion 2.0.0

Description

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

Syntax

array_popback(ARRAY<T> arr)

Parameters

• arr：ARRAY type, the array from which to remove the last 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 last one
• NULL: if the input array is NULL

Usage notes:

• The function removes the last 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 last element from a string array:

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

Remove the last element from an array containing null values:

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

Arrays with only one element return empty arrays:

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

Empty arrays return empty arrays:

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

NULL arrays return NULL:

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

Remove the last element from an IP address array:

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

Remove the last element from a nested array:

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

Remove the last element from a MAP array:

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

Remove the last element from a STRUCT array:

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

Keywords

ARRAY, POPBACK, ARRAY_POPBACK