avoiding duplicate entries???

Anon

I have a table which I input the user information such as ID and passwd.
I want to avoid duplicate user names.
How would I go about doing this?

here is my table:

Thanks.

van__

<?
$stmt = "SELECT uname FROM login WHERE uname='$uname'";
$result = mysql_query($stmt);

if (mysql_num_rows($result)>0) {
$error_msg = "user name is already taken<br>Please enter another user name.";
} else {
$stmt = "INSERT INTO login (uname,passwd) VALUES ('$uname',$passwd')";
$result = mysql_query($stmt);
}

if (isset($error_msg)) {
//do something else;
}
?>

Anon

I had this same problem man- here is how I did it-

run an if statement that checks to see if the username exists, if it does, then redirect them to an error page, or print a statement staing that the username is in use.

Here is an example-

Connect to database

##Select statement:

"SELECT * from TableName where uname = 'enter variable such as $veriuser'";

get the results into an array and assign the variables appropriately.

if ($veriuser == "$uname") {

Print ("I am sorry that username is in use, please us e your browsers back button to try again");

exit;
}

else {

your other staments here}

I hope I explained that well enough, if not let me know

Anon

man I was a little late on that one LOL, van's actually has code- go with his 🙂

Anon

Thanks a bunch, that worked just fine.

[deleted]

This is a very common and very bad way of doing it. It is not multi-user safe, and you will forget to do with check somewhere and f*ck up your database.

Instead, define your uname as 'unique' in your database, that way mysql will simply not allow you to enter a duplicate at all.
If you do enter a duplicate, mysql will give you an errorcode back, which you can identify as 'duplicate entry' and you can still give the user a proper error message.

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