javascript - PHP while 循环导致无限负载

Question

我正在尝试使用 AJAX 上传图像和一些字符串/数字。除了一个非常重要的问题之外，代码运行良好(就像所有内容都进入数据库一样)。我非常希望“字符”变量是唯一的，并且我每次尝试显示错误消息以尝试已采用的字符名称都不起作用。这是我的代码:

AJAX:

function CSubmit() {

clearInterval(MoveDrawTimer);

var a=document.forms['form-id']["thefiles"].value; if (a == "") { document.getElementById("info").innerHTML="You must upload an image."; return };

if (showFileSize() > 5000000) { document.getElementById("info").innerHTML="File is too big. Maximum size is 5,000,000 bytes."; return };

var accepted = [".gif",".png",".jpg",".jpeg"];

if (Ext in oc(accepted) == true) {

var dataURLToBlob = function(dataURL) {
var BASE64_MARKER = ';base64,';
if (dataURL.indexOf(BASE64_MARKER) == -1) {
    var parts = dataURL.split(',');
    var contentType = parts[0].split(':')[1];
    var raw = parts[1];

    return new Blob([raw], {type: contentType});
}

var parts = dataURL.split(BASE64_MARKER);
var contentType = parts[0].split(':')[1];
var raw = window.atob(parts[1]);
var rawLength = raw.length;

var uInt8Array = new Uint8Array(rawLength);

for (var i = 0; i < rawLength; ++i) {
    uInt8Array[i] = raw.charCodeAt(i);
}

return new Blob([uInt8Array], {type: contentType}); }; 

newImage = dataURLToBlob(dataURL); } else { document.getElementById("info").innerHTML="Cannot send file. Check your extensions."; return };


var canvas = document.getElementById("Cinfo");
var context = canvas.getContext("2d");
context.clearRect(0, 0, 400, 400); 

     var TotalSpent = StrPts + IntPts + WisPts + SpdPts + MovPts;

     var theform = document.getElementById("CharName");

     if (theform.value == "") { document.getElementById("info").innerHTML="Your character must have a name."; return }

     if ( /[^a-zA-Z0-9]/.test(theform.value) ) {
    document.getElementById("info").innerHTML="Name must contain only letters and / or numbers."; return }

     if (theform.value.length > 14) { document.getElementById("info").innerHTML="Character names must be 14 characters max."; return }

    if (TotalSpent !== 2) { document.getElementById("info").innerHTML="You must spend exactly 2 points."; return }


 var fd = new FormData();
 fd.append('data', newImage);
 fd.append('character', theform.value);
 fd.append('str', StrPts);
 fd.append('int', IntPts);
 fd.append('wis', WisPts);
 fd.append('spd', SpdPts);
 fd.append('mov', MovPts);



    //beginning of server transmission. above is javascript front end authentication.


              //sending the following information:


              //theform.value // character name
              //StrPts, IntPts, WisPts, SpdPts, MovPts // the character stats

               var xmlhttp;

               if (window.XMLHttpRequest)
                  {       // code for IE7+, Firefox, Chrome, Opera, Safari
                  xmlhttp=new XMLHttpRequest();
                  }
                  else
                  {       // code for IE6, IE5
                  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP"); }


               xmlhttp.onreadystatechange=function(){ xmlhttp.addEventListener("progress", document.getElementById("info").innerHTML="Please wait . . ." , false);
                                                      if (xmlhttp.readyState==4 && xmlhttp.status==200) {
                                                      if (xmlhttp.responseText.length <= 14) {
                                                          document.getElementById("info").innerHTML="Congratulations, " + xmlhttp.responseText + " has been approved.";
                                                          SelectScreen();} } }


               xmlhttp.open("POST","CHunique.php",true);
               xmlhttp.send(fd);

};

如您所见，我将所有内容附加到表单中，然后将其发送到 CHunique.php，如下所示(当前用于演示问题的不完整测试页):

<?php



@$con=mysqli_connect("$db_host","$db_username","$db_pass", "$db_name") or die ("Could not    connect to the database. Please try again later.");

mysqli_set_charset($con,"UTF8");

$Err = "fine";

session_start();
$login = $_SESSION['account'];




$CHresult = mysqli_query($con,"SELECT * FROM CHstats");


while($row = mysqli_fetch_array($CHresult)) {

$thecharacters = $row['character'];

if (strtolower($character) === strtolower($thecharacters)) { $Err = " Character name already in use."; break; }; }

这里的问题是我根本没有从服务器得到任何响应。它无限地停留在其“进度”功能上，也就是说“请稍等……”这对于我在 php 页面上尝试的所有 while 循环都是如此……服务器只是卡在加载中。这是一个很大的问题，因为我需要使用 while 循环来遍历所有字符，以查看用户名是否唯一。

再次，一切工作正常，包括图像上传，除了此检查。这个检查非常重要，我想知道为什么我在 php 页面中尝试的每个 while 循环都会导致无限的加载时间？请帮忙。

另请记住，我不使用 JQuery。

Answer 1

为什么不直接更改查询来为您完成工作，在 PHP 中进行比较并没有真正意义

$query = sprintf("SELECT * FROM CHstats WHERE LOWER(character) = LOWER('%s')", $thecharacters);
$result = mysqli_query($con, $query);
if(mysqli_num_rows($result) > 0){
   // duplicate character name
}

此外，您确定 while 循环是导致页面挂起的原因吗？很可能未建立与 mysql 的连接或需要很长时间。如果您还没有这样做，请在代码中移动一个 die 语句，看看它是在哪里挂起的。