The array_column function returns an array of values representing a single column from the input array.

    
    $records = array(
        array('id' => 2135,'first_name' => 'John','last_name' => 'Doe'),
        array('id' => 3245,'first_name' => 'Sally','last_name' => 'Smith'),
        array('id' => 5342,'first_name' => 'Jane','last_name' => 'Jones'),
    );

    $first_names = array_column($records, 'first_name');

    print_r($first_names);

    // Array
    // (
    //    [0] => John
    //    [1] => Sally
    //    [2] => Jane
    //);