Question

我已经创建了一个表单并使用php来检查数据库中是否存在用户名，如果是，那么表单将不会提交并回显用户名已被删除的表单，如果我填写表单并提交它有一个我知道的名字在数据库中，我得到的错误说用户名已经存在，但我也得到了说明的文字..感谢您注册

基本上它正确显示错误，但它仍然将所有数据提交到数据库

你能在我的代码中看到导致这种情况的任何内容吗？

//Check to see if the username is already taken
$query = "SELECT * FROM clients";
$result = mysql_query($query) or die(mysql_error()); // Get an array with the clients
while($row = mysql_fetch_array($result)){ // For each instance, check the username
if($row["username"] == $username){
    $usernametaken = true;
}else{$usernametaken = false;}
}

// If the username is invalid, tell the user.
// Or else if the password is invalid, tell the user.
// Or else if the email or PayPal address is invalid, tell the user.
// Else, if everything is ok, insert the data into the database and tell
// the user they’ve successfully signed up.

if($usernametaken)
{
echo "That username has been taken.";
}

if(!preg_match('/^[a-zA-Z0-9]+$/', $username ))// If our username is invalid
{
echo "The username can only contain letters or numbers";    // Tell the user
}
 else if(!preg_match('/^[a-zA_Z0-9]+$/', $password ))// If our password is invalid
{
echo "The password can only contain letters or numbers";    // Tell the user
}
// If our email or PayPal addresses are invalid

else if(!preg_match("/^[_a-z0-9-]+(.[_a-z0-9-]+)*@[a-z0-9-]+(.[a-z0-9-]+)*(.[a-z]{2,3})$/", $email))
 {
 return "The email or PayPal address you entered is invalid."; // Tell the user
 }
 else{

// Inserts the data into the database
$result = mysql_query("INSERT INTO clients (client_ID, username, password, email, paypal)"."VALUES ('', '$username', '$pw', '$email', '$paypal')"); 

echo "Thank you for signing up.";
}

?>

Answer 1

如果用户名不好，你需要突破你的功能。如果你不希望你的最后一行运行，你可以在preg匹配之前添加else。基本上你的程序流程是

//if username taken
//if bunch of cases
//else add client

你的两个if语句没有任何区别。

你的SQL语句也是一个熊。您循环遍历数据库中的每个客户端以查看它是否重复。只需添加where语句

即可

$query = "SELECT * FROM clients WHERE clientName = '$clientName'";

Answer 2

如果发现用户名已被删除，则没有任何内容可以告诉脚本停止执行。像这样重构你的if-else语句：

if($usernametaken)
{
    echo "That username has been taken.";
} else {
    // If username is not taken...
}

Answer 3

除了使用其他几个ifs，我建议您使用例外情况。

演示：

   <?php
    try
    {
      if ($usernametaken) throw new Exception('That username has been taken.');


    // If we've reached here we know data has been checked properly
    $result = mysql_query("INSERT INTO clients (client_ID, username, password, email, paypal)"."VALUES ('', '$username', '$pw', '$email', '$paypal')"); 

    echo "Thank you for signing up.";

    }
    catch (Exception $e)
    {
      echo $e->getMessage();
    }
?>

如果重复用户名，表单应显示警告

3 个答案: