aopil

SELECT userid
FROM tbl 
GROUP BY userid
HAVING COUNT(userid) = 1;

а для более старых версий невозможно выполнить то, что я хочу?

SELECT *
FROM services
JOIN (
    SELECT *,
           @row_number := CASE WHEN service_id = @service_id
                               THEN @row_number + 1
                               ELSE 1
                               END rownumber,
           @service_id := service_id
    FROM orders
    CROSS JOIN (SELECT @service_id := 0, @row_number := 0) init_vars
    ORDER BY service_id, id DESC
    ) enumerated_orders USING (service_id)
WHERE enumerated_orders.rownumber <= services.service_limit

$rsMyCredits = $objDBCD14->queryUniqueObject(
    "SELECT Balance FROM tbl_users WHERE UserId = '" . $rs->UserId . "' FOR UPDATE"
);

(new DateTimeImmutable($array["Date"]))->format('F d, Y');

<?php
$p = '/^(.{5})(.*\/R)$/';
$a = [
    'ORZD3MLD/R',
    'ORZD3ML/R',
    'FVAJ2J/R',
];

$r = \array_map(static fn ($l) => \preg_replace($p, '$2', $l), $a);

var_dump($r);

let ids = [...document.querySelectorAll('#myTable tr')].map(x => x.id);
// или
let ids = $('#myTable tr').map(function () {return this.id;})).get();

<input value="<?php echo htmlentities($description); ?>" type="text">

echo '<tr><td nowrap="nowrap" data-sort="2020-04-01">';
echo $date;
echo '</td><td>';

<?php
$date = new DateTime();
$date->setTimestamp(1644537600000/1000);
echo $date->format('Y-m-d') . "\n";

$phone = "+3581856";
$code = ltrim($phone, "+");
$countries = [];
foreach($allCountries as $c) {
  if (strpos($code, $c[2]) === 0) {
    $countries[] = $c;
  }
}