comparing input field with database

animaus

I have made a HTML-form where a user can make some indications into text-fields which should be send to a database like a member or a client. But he only should be allowed to do this once.
So I have to compare his statements with the database, are they already existing?
So my Script is like the following:

<head>
<title></title>
<?
mysql_connect("localhost","root","");
mysql_select_db("member");

if($submit)
{
$result = mysql_query("SELECT ID, name, email FROM kennung WHERE name='$name'");
while($row = @mysql_fetch_array($result))
{
if ($name == $row["name"])
{
echo $row["ID"];
echo " - ";
echo $row["name"];
echo "<br>\n";
echo "Already existing!<br>\n";
}
}
}
?>
</head>
<body>
<form action="<? $PHP_SELF ?>" method="post">

<table>
<tr><td>Name:</td>
<td><input type="Text" name="name" value="<? $name ?>" size="30" ></td></tr>
<tr><td>Email:</td><td><input type="Text" name="email" value="<? $email ?>" size="50" ></td></tr>
<tr><td> </td>
<td><input type="Submit" name="submit" value="Send"></td></tr>
</table>
</form>
</body>

It doesn't work. I don't get a warning or an error message - I get nothing.

Could you help me - find my mistake please.

Animaus

Anon

I would make a only HTML-Page with Form-Tags like this: <form action="entry.php" method="post">

and in the PHP-Script you can write something like this:

$host = "www.host.com";
$user = "insert username here";
$passwd = "insert pass here";
$dbname = "insert dbname here";
$conn = @mysql_connect($host, $user, $passwd);
if($conn){
mysql_select_db($dbname, $conn);
}else{
die("Oops, something goes wrong");
}

$sql = "INSERT INTO tablename (v_name,n_name,e_mail,street,plz,location) VALUES
('$v_name','$n_name','$e_mail','$street','$plz','$location')";

Anon

Might help to default the $name and $email when the page is first accessed (on am "else" after the "if ($submit)..."). Otherwise they are undefined variables.

animaus

Thanks for your reply.
I have made a script like your proposal bevor I have posted my question here.
It works well - I can insert into the database - but the problem is that I can insert the same name and same email or password as often as I press the Button.

I have made a script to read the database - it runs very well.

But I want to compare whether the data already axists in the database or not before insert them again.

My question ist, how can I do that? How can I get the information "Your data already exists!" ?

With my script it doesn't work. Do you have any idea?

Animaus

animaus

In a second version of my script (which I didn't place here, I had an else like this:

else
{
$sql = "INSERT INTO tablename.....";
}

But with this the data will be written into the database without comparing. So that the data are in the database twice as much - and that should not be.

Any idea?

Animaus