首页 \ 问答 \ 检查数据库中是否已存在用户名(Check if username already exist in DB)

检查数据库中是否已存在用户名(Check if username already exist in DB)

我尝试在注册表单中验证用户名字段,并检查所选用户名是否已存在于数据库中,但无法按预期工作。 我不知道如何解决这个问题。 这是来源

$query = "SELECT * FROM users WHERE username = :username";
$sq = $pdo->prepare($query);
$sq->execute(array(
         ':username'    => $username                                
        ));
$res=$sq->fetch();
if (!$res) {
    echo ' Database Error Occured ';
}
else { echo "username already exist in database"; }

if ($res === 0) {
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $pdo->beginTransaction();
    try 
    {
         $sql = "INSERT INTO users ( username, password, email, path)
                            VALUES (:username, :password, :email, :path)";

                $q = $pdo->prepare($sql);
                $q->execute(array(
                    ':username' => $username,
                    ':password' => $password,
                    ':email'    => $email,
                    ':path'     => $path                                
                    ));                 

                $lastInsertID = $pdo->lastInsertId();
                $sql = $pdo->prepare("UPDATE users SET level=:user_id WHERE user_id=:user_id");
                $sql->execute(array(
                    ':user_id'  => $lastInsertID
                    ));
                $pdo->commit();     
     }

发生了什么事情,当我点击提交按钮如果我输入的用户名存在我的username already exist in database但如果我输入另一个不存在我得到Database Error Occured


I trying to validate username field in register form and to check if the selected username already exist in DB but doesn't work as expected. I'm not sure how to fix this. Here is the source

$query = "SELECT * FROM users WHERE username = :username";
$sq = $pdo->prepare($query);
$sq->execute(array(
         ':username'    => $username                                
        ));
$res=$sq->fetch();
if (!$res) {
    echo ' Database Error Occured ';
}
else { echo "username already exist in database"; }

if ($res === 0) {
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $pdo->beginTransaction();
    try 
    {
         $sql = "INSERT INTO users ( username, password, email, path)
                            VALUES (:username, :password, :email, :path)";

                $q = $pdo->prepare($sql);
                $q->execute(array(
                    ':username' => $username,
                    ':password' => $password,
                    ':email'    => $email,
                    ':path'     => $path                                
                    ));                 

                $lastInsertID = $pdo->lastInsertId();
                $sql = $pdo->prepare("UPDATE users SET level=:user_id WHERE user_id=:user_id");
                $sql->execute(array(
                    ':user_id'  => $lastInsertID
                    ));
                $pdo->commit();     
     }

What is happening is when I click on submit button If I'm entered username that exist I got username already exist in database but if I enter another which doesn't exist I got Database Error Occured


原文:https://stackoverflow.com/questions/27987109
更新时间:2020-03-23 22:27

最满意答案

你必须替换它

 if (!$res) {
        echo ' Database Error Occured ';
    }
    else { echo "username already exist in database"; }
if ($res === 0) {

这样

if ($res) {
    echo "username already exist in database";
}else{

You have to replace this

 if (!$res) {
        echo ' Database Error Occured ';
    }
    else { echo "username already exist in database"; }
if ($res === 0) {

by this

if ($res) {
    echo "username already exist in database";
}else{
2015-01-16

相关文章

更多

最新问答

更多
  • 如何避免MDIParent表单调整大小(How do I avoid MDIParent form from resizing)
  • Angular自定义指令调用另一个自定义指令(Angular custom directive calling another custom directive)
  • 如何通过参数将文本解析并附加到SQL Server 2005中的存储过程(How to Parse and Append text to a stored procedure in SQL Server 2005 via a parameter)
  • OpenCV中心Homography(OpenCV Center Homography)
  • 如何在linux shell脚本中计算日期-N?(How to calculate date -N in linux shell scripting?)
  • 如何使用Devise创建用户配置文件?(How Do I Create a User Profile With Devise?)
  • 清理模式以管理树上的多步异步过程(Clean pattern to manage multi-step async processes on a tree)
  • 场景的角色(Role of the Scene)
  • 组件中的Angular 2组件[重复](Angular 2 Component In Component [duplicate])
  • jsPlumb draggable element javascript函数(jsPlumb draggable element javascript function)
  • MVC4:ViewModel(带有radiobuttonlist)在HttpPost之后为空(MVC4: ViewModel (with radiobuttonlist) is empty after HttpPost)
  • 如何在同一帐户上设置“Dev repo”(在prod和团队之间)(How to set up a “Dev repo” (between the prod and the team) on the same account)
  • 如何在tcl中将eth0配置为发送方udp端口(how to configure eth0 as a sender udp port in tcl)
  • 如何使用预定义文本替换来自数据库的部分结果(How do I replace part of result coming from Database with predefined text)
  • Selenium Java注入了新的Javascript函数(Selenium Java inject new Javascript function)
  • 使用.on的多个下拉菜单选择文本仅适用于第一个下拉列表(Multiple Dropdowns Menu Selection text using .on works only on first dropdown)
  • 快速将黄土曲线添加到大型数据集图中的方法(Quick way to add loess curve to large data set graph)
  • FilteringSelect in mvc(FilteringSelect in mvc)
  • 在Delphi XE2中开发Mac或iOS应用程序需要哪些硬件/软件?(What hardware/software is necessary to develop Mac or iOS apps in Delphi XE2?)
  • 在原型的构造函数中初始化属性时获取“未定义”(Getting 'undefined' when a property is initialized in the constructor of a prototype)
  • 通过越狱加载的应用程序的Documents文件夹位置(Location of Documents folder for an app loaded via jailbreak)
  • 在OpenGL中使用可编程和固定管道功能(Using both programmable and fixed pipeline functionality in OpenGL)
  • 将任何用户输入重定向到单独的底层程序(redirect any user input to a separate underlying program)
  • 编辑文本不能正常工作android(Edit texts not working properly android)
  • “user_denied”Facebook应用页面上的Facebook用户区域设置(Facebook user locale on “user_denied” facebook app page)
  • 在大图像中找到小的部分透明图像的坐标(find coordinates of small partially-transparent image within a large image)
  • 我如何在cakephp 3.1中获得完整的相对路径?(How i can get full relative path of image in cakephp 3.1?)
  • 如何保存拖动标记的新本地化?(How to save new localization of dragged marker?)
  • MySQL UPDATE vs INSERT和DELETE(MySQL UPDATE vs INSERT and DELETE)
  • 在执行查询之前,在SQLAlchemy模型中将datetime转换为unix时间戳?(Convert datetime to unix timestamp in SQLAlchemy model before executing query?)