试图让PHP检查数据插入中的重复项

` ？>`

到目前为止，我的数据库连接还不错，当我到达$doop时

mysql_connect("host","admin","password");//database connection

mysql_select_db("dbname");


$order="INSERT INTO members (username, password) VALUES ('$_POST[username]','$_POST[password]')";



$doopquery = mysql_query("SELECT username FROM members WHERE username='$_POST[username]' ")

if ($doopquery) {
    echo("Username Taken");
} else {
    $result = mysql_query($order);
    echo("Account Registered");
}

用户名周围缺少“标记”

失踪；在$doopquery结束时，按如下方式操作：

$username=mysql_real_escape_string($_POST['username']);
$doopquery = mysql_query("SELECT username FROM members WHERE username='$username' ");
if(mysql_num_rows($doopquery)==0){
     //username not found
}
else{
      //username already exists
 }

---

这到底是怎么回事？您可以包括您的错误消息和您的目标吗？只需在数据库中使username列唯一，并捕获errorsDanel，如下面的答案所示，请确保在将数据放入查询之前清理任何用户输入（例如，使用mysql\u real\u escape\u string）。如果不这样做，您将受到一个简单但可能非常有害的SQL注入攻击。如果用户名是迈克的天使？一点解释会很有帮助。你改变了什么？这是如何解决问题的？

$username = mysql_real_escape_string($_POST['username']);
$password = mysql_real_escape_string($_POST['password']);

$query = "SELECT username FROM members WHERE username='{$username}'";
$result = mysql_query($query);
if(mysql_num_rows($result) > 0) {
  echo "Username Already Taken!";
}else{
  $query = "INSERT INTO members (username, password) VALUES ('{$username}','{$password}')";
  if(mysql_query($query)) {
    echo "Account Registered!";
  }else{
    echo "Account Register Failed!";
  }
}