PHP 8.1: MySQLi: fetch_column function

Another suggestion made by Kamil Tekiela was included in the PHP 8.1 release.
Starting with this release, one more method has become available in the mysqli class - the fetch_column() method previously implemented in the PDO library.

Lets create simple table for our tests:

create table persons (
    id int primary key, 
    name varchar(64),
    age tinyint
);

insert into persons values (10, 'Alice', 18), (20, 'Bob', 22);

+====+=======+=====+
| id | name  | age |
+====+=======+=====+
| 10 | Alice | 18  |
| 20 | Bob   | 22  |
+----+-------+-----+

$result = $mysqli->query("SELECT name FROM persons WHERE id = 10");

echo $result->fetch_column();

You can test the above code here

If the query returns several columns, the fetch_column(n) function can return the value from the column whose number is passed as a function parameter (column numbering starts from 0).

$result = $mysqli->query("SELECT name, age FROM persons WHERE id = 10");

echo $result->fetch_column(1);

Just like with other fetch_* methods this one will also move the internal result pointer to the next row when called. So you can not use fetch_column(i) for loop thought one record columns.
Next example explain this error:

<?php
$result = $mysqli->query("SELECT name, age FROM persons");

$name = $result->fetch_column(0);
$age  = $result->fetch_column(1);

// Returns Alice  name with Bob's age
printf("Name: %s, age: %d", $name, $age);

Test PHP code online