Echo database value and create or update record - php

Question

I created a sort of (available / unavailable) for staff to store the start and end times/dates of each working day.
Here are my goals:
After their personal id is being scanned, they will see their own picture. Also the database will do the following:
Database checks or there is any record for the current date.Yes = update stop time and date. No = Create new entry.
Code:
if (isset($_POST['action'])) {
$queryRegistration = "SELECT id, number, startdate FROM timeRegistration";
$resultRegistration = mysqli_query($conn, $queryRegistration);
while($row = mysqli_fetch_assoc($resultRegistration)) {
if ($row['number'] == $staffNumber) {
if ($row['startdate'] == $currentDate) {
echo $row['number'].' '.$row['id'];
echo '<div class="boxPersons">My Picture</div>';
}
}
}
}
Goal 1: Does not work. As it creates more divs. How can I manage it only creates one div?
Goal 2: I want to update or create it with functions like:
function newEntryDate() {
$sql = 'INSERT INTO timeRegistration (id, number, startdate, enddate, starttime, endtime, value) VALUES (NULL, "'. $staffNumber .'", "'. $currentDate .'", "", "'. $currentTime .'", "", "")';
return $sql;
}
Question: How can I make sure this works within my script? I don't know how to start.

Answer 1

Do something like this.
if your query is retrieving more than 1 row set a limit in query.
it is better to not use if statement in while loop.
if (isset($_POST['action'])) {
$queryRegistration = "SELECT id, number, startdate FROM timeRegistration where startdate =".$currentDate." AND number=".$staffNumber." limit 1;";
$resultRegistration = mysqli_query($conn, $queryRegistration);
$i=0;
while($row = mysqli_fetch_assoc($resultRegistration)) {
echo '<div class="boxPersons">My Picture</div>';
$i++;
}
if($i>0){
newEntryDate();
}