无法执行INSERT INTO成员

这应该会向您说明查询失败的原因，并且至少可以防止一些安全问题：

小改进

// Run by each $_POST entry and set it to empty if not found
// Clean the value against tags and blank spaces at the edges
$dataArr = array();
foreach($_POST as $key => $value) {
    $dataArr[$key] = ($value == "undefined") ? '' : strip_tags(trim($value));
}
// try to perform the INSERT query or die with the returned mysql error
$query = mysql_query("
  INSERT INTO members 
  (user, pass, mail, country, city, www, credo)
  VALUES (
    '".$dataArr["user"]."',
    '".$dataArr["pass"]."',
    '".$dataArr["mail"]."',
    '".$dataArr["country"]."',
    '".$dataArr["city"]."',
    '".$dataArr["www"]."',
    '".$dataArr["credo"]."'
  )
") or die ("Error:<br/>".mysql_error());

介质改进

// Run by each $_POST entry and set it to empty if not found
// Clean the value against tags and blank spaces at the edges
$dataArr = array();
foreach($_POST as $key => $value) {
    $dataArr[$key] = ($value == "undefined") ? '' : strip_tags(trim($value));
}
// escape everything
$query = sprintf("
    INSERT INTO members 
    (user, pass, mail, country, city, www, credo) 
    value ('%s', '%s', '%s', '%s', '%s', '%s', '%s')",
    mysql_real_escape_string($dataArr["user"]), 
    mysql_real_escape_string($dataArr["pass"]), 
    mysql_real_escape_string($dataArr["mail"]), 
    mysql_real_escape_string($dataArr["country"]), 
    mysql_real_escape_string($dataArr["city"]), 
    mysql_real_escape_string($dataArr["www"]), 
    mysql_real_escape_string($dataArr["credo"])
);
// try to perform the INSERT query or die with the returned mysql error
$result = mysql_query($query) or die ("Error:<br/>".mysql_error());

高级改进

如果你正在启动一个新项目，或者你仍然可以改变你的方式，我强烈建议你使用PHP PDO来防止与你正在使用的当前数据库连接相关的许多安全问题。

INSERT INTO members 
(user, pass, mail, country, city, www, credo)
VALUES  
('".$_POST['user']."','".$_POST['pass']."', '".$_POST['mail']."',
'".$_POST['country']."', '".$_POST['city']."', '".$_POST['www']."', '".$_POST['credo']."')")

只是一个简短的警告。将POST值直接插入数据库可能会导致安全漏洞。在将所有用户输入插入数据库之前，请确保对其进行验证和筛选。

您的Sql查询错误。此处

VALUES  ('$_POST[user]')

你必须使用

 $_POST['user']

您正在将值直接插入数据库中。。！！！这完全是一种糟糕的感觉。让它逃离

$user = mysql_real_escape_string(trim($_POST['user']));
$pass = mysql_real_escape_string(trim($_POST['pass']));
$mail = mysql_real_escape_string(trim($_POST['mail']));
$country = mysql_real_escape_string(trim($_POST['country']));
$city = mysql_real_escape_string(trim($_POST['city']));
$www = mysql_real_escape_string(trim($_POST['www']));
$credo = mysql_real_escape_string(trim($_POST['credo']));

然后将其插入数据库，

$query = mysql_query("INSERT INTO members 
        (user, pass, mail, country, city, www, credo)
        VALUES  ($user,$pass, $mail,$country, $city, $www, $credo)")
        or die ("Error - Couldn't register user.");

该代码现在是安全的，可以插入数据库，并且是一个干净的代码。。