PDO get first element of a SQL query result

Question

How do I get 7 from the table below with a query like:

SELECT name from table WHERE id = 3

That is, the first item of the array.

id name
1   [2,3]
2   [3,5,6]
3   [7,8]

This is how the PDO is looking like. I can get the

$db = new PDO('...');
$sth = $db->prepare('SELECT `name` AS grupo
FROM `table`
WHERE `id` =3');

$sth->execute();
$resultado= $sth->fetch();
echo ($resultado)[0];

Which is returning:

[7,8]

Answer 1

Have a look at PDO::fetchColumn .

Returns a single column from the next row of a result set

EDIT:

echo json_decode($sth->fetchColumn(), true)[0];