使用PHP中的数据表计数和最大值

For a house project, I'm using Datatable because it is very user friendly. This example is a clean code which I work.

I extract 2 columns from my database : "login" and "date_visit" .

$table = 'name_table';
$primaryKey = 'id_table';
$columns = array(

    array(
        'db' => '`table`.`login`',
        'dt' => 0, 'field' => 'login',
        'formatter' => function( $d, $row ) {
            return $d;
            }
    ),

    array(
        'db' => '`table`.`date_visit`',
        'dt' => 1, 'field' => 'date_visit',
        'formatter' => function( $d, $row ) {
            setlocale(LC_TIME, 'fra');
            if (date('Y', $d) != date('Y', time())) {
                return ucwords(utf8_encode(strftime ("%A %d %B %Y à %H:%M" , $d)));
            } else {
                return ucwords(utf8_encode(strftime ("%A %d %B à %H:%M" , $d)));
            }
         }
    )
);

$sql_details = $mysqli->arrayMysqli();

require($_SERVER['DOCUMENT_ROOT'].'/classes/ssp.class.php');

$joinQuery = 'FROM `'.$table.'`';
$extraWhere = '`table`.`login` = '.$function->getLogin();

echo json_encode(
    SSP::simple( $_GET, $sql_details, $table, $primaryKey, $columns, $joinQuery, $extraWhere )
);

I spent the last 2 evenings to look how to retrieve the number of times the user has logged on. So I try to make a "SELECT COUNT (date_visit) ...", but I have not found how to proceed with Datatable.

Also, I would like to understand how is it possible to recover via Datatable the date of the last visit. Same problem here, I did not understand how to make a "SELECT MAX (date_visit) ..."

Please tell us in advance that you are not using the normal SSP class but an extension of it probably this one: https://github.com/emran/ssp/blob/master/ssp.php The one that you use has a column $groupBy = '' use that one to group things.