我想知道是否以及如何检查用户名是否正在使用。
我听说您可以使用jQuery完成此操作，但由于我是初学者，所以我只想简单一些。
我已经尝试过了，但我无法缝制正确。我只是将它连接到mysql数据库，但是由于当一个具有与另一个帐户相同密码的用户名试图登录时，出现了问题，因此我需要这样做来阻止人们添加多个用户名。
这是我注册表格和php的简单代码
<form action="" method="POST">
<p><label>name : </label>
<input id="password" type="text" name="name" placeholder="name" /></p>
<p><label>User Name : </label>
<input id="username" type="text" name="username" placeholder="username" /></p>
<p><label>E-Mail : </label>
<input id="password" type="email" name="email"/></p>
<p><label>Password : </label>
<input id="password" type="password" name="password" placeholder="password" /></p>
<a class="btn" href="login.php">Login</a>
<input class="btn register" type="submit" name="submit" value="Register" />
</form>
</div>
<?php
require('connect.php');
// If the values are posted, insert them into the database.
if (isset($_POST['username']) && isset($_POST['password'])){
$username = $_POST['username'];
$email = $_POST['email'];
$password = $_POST['password'];
$name = $_POST['name'];
$query = "INSERT INTO `user` (username, password, email, name) VALUES ('$username', '$password', '$email', '$name')";
$result = mysql_query($query);
if($result){
}
}
?>最佳答案
对于初学者，您不希望仅依赖于诸如唯一字段之类的东西来进行此操作，当然，您将需要将该属性添加到数据库内的用户名列中，但在此之上，您希望在其上方具有某种正面保护，并且不依赖于数据库在INSERT INTO上抛出错误，您还将想要针对所有这些使用mysqli，而不是旧版本mysql。它很容易被利用，并且不再常见，这是每个文件的外观：
connect.php
<?php
$conn = mysqli_connect("localhost","username","password","database");
// Check connection
if (mysqli_connect_errno())
{
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
?>
register.php
<form action="insertuser.php" method="POST">
Username:
<input type="text" name="username" placeholder="Username" />
<br />
Password:
<input type="password" name="password" placeholder="Password" />
<br />
Name:
<input type="text" name="name" placeholder="Name" />
<br />
Email address:
<input type="text" name="email" placeholder="Email address" />
<br /><br />
<input type="submit" value="Register" />
</form>
<?php
// If there's an error
if (isset($_GET['error'])) {
$error = $_GET['error'];
if ($error == "usernametaken") {
echo "<h4>That username is taken!</h4>";
} elseif ($error == "inserterror") {
echo "<h4>Some kind of error occured with the insert!</h4>";
} else {
echo "<h4>An error occured!</h4>";
}
echo "<br />";
}
?>
Already have an account? <a href="login.php">Login here</a>
insertuser.php
<?php
// Stop header errors
ob_start();
// Check if form has been posted
if (isset($_POST['username'])){
// Requre database connection file
require('connect.php');
// Clean the variables preventing SQL Injection attack
$username = mysqli_real_escape_string($conn, $_POST['username']);
$email = mysqli_real_escape_string($conn, $_POST['email']);
$password = mysqli_real_escape_string($conn, $_POST['password']);
$name = mysqli_real_escape_string($conn, $_POST['name']);
// Check if the username exists
// Construct SELECT query to do this
$sql = "SELECT id FROM user WHERE username = '".$username."';";
$result = mysqli_query($conn, $sql);
$rowsreturned = mysqli_num_rows($result);
// If the username already exists
if ($rowsreturned != 0) {
echo "Username exists, redirecting to register.php with an error GET variable!";
// Redirect user
header('Location: register.php?error=usernametaken');
} else {
// Construct the INSERT INTO query
$sql = "INSERT INTO user (username, password, email, name) VALUES ('".$username."', '".$password."', '".$email."', '".$username."');";
$result = mysqli_query($conn, $sql);
if($result){
// User was inserted
echo "User inserted!";
/* DO WHATEVER YOU WANT TO DO HERE */
} else {
// There was an error inserting
echo "Error inserting, redirecting to register.php with an error GET variable!";
// Redirect user
header('Location: register.php?error=inserterror');
}
}
}
?>
祝您工作顺利，希望对您有所帮助！
詹姆士
关于php - 检查是否使用了用户名，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/35825308/