element_at

description

Syntax

T element_at(ARRAY<T> arr, BIGINT position)

T arr[position]

Returns an element of an array located at the input position. If there is no element at the position, return NULL.

position is 1-based and support negtive number.

notice

Only supported in vectorized engine

example

positive position example:

mysql> set enable_vectorized_engine=true;
mysql> SELECT id,c_array,element_at(c_array, 5) FROM `array_test`;
+------+-----------------+--------------------------+
| id   | c_array         | element_at(`c_array`, 5) |
+------+-----------------+--------------------------+
|    1 | [1, 2, 3, 4, 5] |                        5 |
|    2 | [6, 7, 8]       |                     NULL |
|    3 | []              |                     NULL |
|    4 | NULL            |                     NULL |
+------+-----------------+--------------------------+

negtive position example:

mysql> set enable_vectorized_engine=true;
mysql> SELECT id,c_array,c_array[-2] FROM `array_test`;
+------+-----------------+----------------------------------+
| id   | c_array         | %element_extract%(`c_array`, -2) |
+------+-----------------+----------------------------------+
|    1 | [1, 2, 3, 4, 5] |                                4 |
|    2 | [6, 7, 8]       |                                7 |
|    3 | []              |                             NULL |
|    4 | NULL            |                             NULL |
+------+-----------------+----------------------------------+

keywords

ELEMENT_AT, SUBSCRIPT