- array_map: documentation ( source)
- implode: documentation ( source)
<?php
$input = array(
array(
'id' => 1,
'tag_name' => 'google',
'name' => 'joe'
),
array(
'id' => 500,
'tag_name' => 'technology',
'name' => 'bob'
)
);
echo implode(', ', array_map(function ($entry) {
return $entry['tag_name'];
}, $input));