$data is not returning result - php

Question

I need the $data to return from the database if the data was found from the database, but unfortunately, my code is not working to return the data.
I tried to enter non-exist data, it managed to return the error message but if the data exist, the page displays nothing.
May I know where did I go wrong in my if statement?
Below is my code that contain after the $data return the script will execute.
$day = $_POST['day'];
$month = $_POST['month'];
$year = $_POST['year'];
$dob = implode('/', array($day,$month,$year));
if(isset($_POST['submit'])){
if(empty($_POST['day']) || empty($_POST['month']) || empty($_POST['year'])){
echo "You need to fill in each field.<br /><br />Click here to <b>fill in each field</b> again";
exit;
}
}
//Date that user keyin
$userDate = $dob;
$dateTime = DateTime::createFromFormat('d/m/Y', $userDate);
$myFormat = $dateTime->format('Y-m-d');
//Query string and put it in a variable.
if(isset($_POST['dob_chi'])){
$query = "SELECT * FROM $table_n WHERE dob_chi = :date";
} else {
$query = "SELECT * FROM $table_n WHERE dob_eng = :date";
}
$stmt = $db->prepare($query);
$stmt->execute(array('date' => $myFormat));
$data = $stmt->fetchAll();
if ( !$data ) {
echo 'No data found in database!';
exit;
} else {
return $data=$userDate;
}
//Now we create a while loop for every entry in our DB where the date is match.
while ($row = $stmt->fetchObject()) {
$r1 = $row->rowone;
$r2 = $row->rowtwo;
$r3 = $row->rowthree;
$englishdate = $row->dob_eng;
$chinesedate = $row->dob_chi;
$zodiac = $row->zodiac;
//add all initial data into a matrix variable for easier access to them later
//To access rowone use $rows[0][0], rowtwo $rows[1][0] ect.
//The matrix is an array which contains multiple array. eg. 2-dimensional arrays
//To get all the variables with $r1X simply retrieve the first array of the matrix eg $rows[0]
$rows = array(array($r1),array($r2),array($r3),array());
}
//Similarities between row1 and row2 made me incorporate modulo value as an argument.
function incmod($a, $m){
return ($a % $m) + 1;
}
Thank you for your time

Answer 1

Get rid of the line:
return $data=$userDate;
because it's ending your script and also overwriting the $data variable.
Change:
$data = $stmt->fetchAll(PDO::FETCH_OBJ);
Then change the line:
while ($row = $stmt->fetchObject()) {
to:
foreach ($data as $row) {