Question

This is the problematic part of code:

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

I got the die error.
How could I find more specific part which cannot be executed ?
I tried to eliminate fields one by one – without result.

Answer 1

This should present you the reason behind your failed query, and at the very least prevent some security concerns:

Small Improvement

// 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());

---

Medium Improvement

// 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());

---

Advanced Improvement

If you’re starting a new project, or at a point where you can still change your ways, I vividly recommend the use of PHP PDO to prevent many security issues related the current database connection you’re using.