AJAX响应和PHP循环

Question

I am using PHP to retrieve some records from a MySQL database, I would like to send these to my AJAX and loop through them, in order to prepend rows to an existing table.

However I can only see the last (most recent) record returned from my query. Could someone please point out where I am going wrong?

AJAX:

$.ajax({
    type: "POST",
    url: 'feed.php',
    data: {lastSerial: true},
    dataType: 'json',
    success: function(data){
        console.log(data); // logs `{Direction: "O", CardNo: "02730984", SerialNo: 20559303}`
        $.each(data, function(key, value) {
            // here I want to loop through the returned results - for example
            $("#transactionTable").prepend('<tr><td>'+ SerialNo +'</td><td>'+ CardNo +'</td><td>'+ Direction +'</td></tr>');
        });
       }
   });

feed.php

if(isset($_POST['lastSerial']) && $_POST['lastSerial'] == true) {
  $query = "SELECT TimeStamp, Direction, CardNo, SerialNo FROM Transactions";
  // this query returns approx. 20 results
  $stmt = $conn->prepare($query);
  $stmt->execute();
  $result = $stmt->get_result();
  while($row = $result->fetch_assoc()) {
        $data["Direction"] = $row['Direction'];
        $data["CardNo"] =   $row['CardNo'];
        $data["SerialNo"] = $row['SerialNo'];
  }
  echo json_encode($data);
}

Also in my PHP, should I be using a while or if statement?

Answer 1

You're using a single $data object and resetting its contents each time. You want to build an array of objects:

$data = array();

while($row = $result->fetch_assoc()) {
  $data[] = array( 
    "Direction" => $row['Direction'],
    "CardNo"    => $row['CardNo'],
    "SerialNo"  => $row['SerialNo']
  );
}

echo json_encode($data);

Followed by:

success: function(data) {
    $.each(data, function(key, value) {
        $("#transactionTable").prepend(
          '<tr><td>' + value.SerialNo + '</td>' +
          '<td>' + value.CardNo + '</td>' +
          '<td>'+ value.Direction +'</td></tr>');
    });
}