试图将 MySQL 查询的结果放入 JavaScript 数组

Question

I've got a MySQL database of offices with geo data. I'm trying to get a list of the office cities into a JavaScript array. For now, I just wanted to set up a simple $.ajax() to log the list into the console, but it's returning null. I'm just running my JavaScript function "query()" in console after the page loads.

Here's my JavaScript.

function query() {
  $.ajax({
    url: "query.php",
    method: "POST",
    dataType: 'json',
    success: function(data) {
      let output = JSON.parse(data)
      console.log(output)
    }
  })
}

Here's query.php

<?php
include 'database.php';
$sql="SELECT `Office City` FROM `offices`";
$result = $link->query($sql);

if ($result) {
    while($row = $result->fetch_assoc()) {
        array_push($result_array, $row);
    }
}
header('Content-type: application/json');
echo json_encode($result_array);
$link->close();
?>

Here's database.php. I'm able to write to MySQL using this PHP, so I assume it's correct.

<?php
    $hostname = "hostus.mostus.com";
    $username = "name";
    $password = "pw";
    $database = "db";
    $link = mysqli_connect($hostname, $username, $password,$database);
    if (mysqli_connect_errno()) {
        die("Connect failed: %s\n" + mysqli_connect_error());
        exit();
     }

When I run query() in the console, it responds "undefined" then null.

Answer 1

Your sql is invalid. I would also init the $result_array before. Currently if the result is empty, you are returning null.

<?php
include 'database.php';
$sql="SELECT `Office`, `City` FROM `offices`";
$result = $link->query($sql);

$result_array = [];
if ($result) {
    while($row = $result->fetch_assoc()) {
        array_push($result_array, $row);
    }
}
header('Content-type: application/json');
echo json_encode($result_array);
$link->close();
?>