How do I capture only numbers out of a string? PHP

How do I capture only numbers out of a string?   My attempt (intval($ponum) == 0) did not work.

Currently I am getting PO Numbers like:  
 
1193 CANCELED 3 ON BKO ---    (I Need to remove "CANCELED 3 ON BKO" for example.  I only need 1193)

1196|   ---   (I Need to remove "|" for example.  I only need 1196)


Thanks!

$query1 = $conn->query("SELECT * FROM Outdoor_Invoices
LEFT JOIN oc_order ON oc_order.order_id = Outdoor_Invoices.PO2Comment");


    while ($row1 = $query1->fetch(PDO::FETCH_ASSOC))
    {	
        $orderid = $row1['order_id'];
	$ponum = $row1['PO2Comment'];    // I need to capture the first 4 numbers only from this variable, No text.
	$InvAmt = $row1['InvAmt'];
	$OrderTotal = $row1['total'];
	$GrossProfit = ($OrderTotal - $InvAmt);
	$CreditCard = ($OrderTotal * .029) + .30;
	$NetProfit = ($GrossProfit - $CreditCard); 
	$orderstatus = $row1['order_status_id'];
    


if ($orderstatus != 3) {
continue;
} elseif (intval($ponum) == 0) { 
continue;
} else {

 
$conn->query("UPDATE `Outdoor_Invoices` SET OrderTotal = $OrderTotal, GrossProfit = $GrossProfit, CreditCard = $CreditCard, NetProfit = $NetProfit WHERE PO2Comment = '$ponum'");
}						

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