validate username

[columbo1977]

Hi

Can anyone help. Attached is the registration form from a site I am building, the form is validated and the passwords are checked but I now need to check to make sure no-one enters the same username in the database.

Can anyone tell me how, as you can see from the function validuser() I have already been trying to do this.

Site has been built with PHP and MySQL.

Click on the link below for the registration form.

http://www.yousendit.com/transfer.php?action=download&ufid=B9E13F41321AA4B9

Thanks

Columbo1977

 

[sleipnir214]

The only user-defined function named "validuser" in your download is a mishmash of JavaScript and ill-formed pseudo-PHP.





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[columbo1977]

i know,i am new to this and trying to get it working.

 

[sleipnir214]

Do you understand that JavaScript runs on the browser and PHP on the server? And that because of this, you can't just call PHP code from within a PHP page like you can JavaScript?





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[columbo1977]

yes i understand, so have you any ideas on how i can check if the user that is registering is on the database already? and then ask the user to change the username?

cheers

Columbo1977

 

[sleipnir214]

Typically, a user fills out a form on a static HTML page and submits that form to a PHP script. In a case such as you describe, where a user could take multiple times entering data and having the script return errors, I use a script that creates HTML that submits back to itself.

The PHP script takes the basic form of:

<?php
if (/* form was submitted */)
{
   //validate input
   if (/* input validated */)
   {
      //Use Location: header to send browser
      //next page
   }
   else
   {
      //display HTML with error and with form-
      //fields prepopulated with submitted values
   }
}
else
{
   //display blank form
}
?>

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[columbo1977]

but how do i get it to check the sql database to see if the username has already been used?

 

[jpadie]

use a call to the database

$q_result = mysql_query("select count(*) from usertable where username='".mysql_escape_string(trim($_POST['username']))."'");
$result = mysql_result ($q_result, 0, 0);
if ($result > 0)
{  echo "user name already in use"; }
else
{  echo "user name is free to use"; }

 

[columbo1977]

Hi

Where would i put that in my code?

 

[sleipnir214]

Unknown.

I would put it in my code at about the place where the comment:

//validate input

appears. After all, that's the code that validates the input, isn't it?



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