Form submit only once

vgamemaster

Okay so I have a registration system that works great, and I have a totally separate form that posts some information to a database. This form automaticly submits your username to the database. I want to limit this form to only submit per one username.

How could I go about doing this?

I realize I worded that a little wierd so if anyone need a little clarification I would be happy to explain it more.

Thanks

devinemke

once the form is submitted run a query to see if that username is already in the database and spit back an error if it is.

vgamemaster

Okay, I am kind of a noob with this so I don't exactly know how to do that.
Do I have the right idea?

<?php 
			include 'dbconnect.php';
			$dbname ='teamregister';
		mysql_select_db($dbname);
		$query = mysql_query("SELECT captain FROM Teams");
		$result = mysql_result(mysql_query($query)),0,0);
		if($result ==1)
		{
		 //dont show form
		 }
		 else
		 {
		 //show form
		 }  ?>

brendan2b

The way I would personally do it is write a isUnique function that will return either true or false depending on if the user is found in the database.

Look below for an example.



function isUnique($username)
{
       //connect to your database and all that good stuff

   // make sure the username doesn't consist of illegal sql characters
   $username = mysql_real_escape_string($username);

    $query = mysql_query("SELECT * FROM `yourUsersTable` WHERE `usernameField` = '$username'") or die("Cannot Execute isUnique");

    if($query)
    {
          if(mysql_num_rows($query) > 0)
                    return 0;
          else 
                    return 1;
    }
    else
         return 0;
}


if(isset($_POST['yourForm']))
{

 // runs your checks to make sure the input is a valid username
 $username = trim($_POST['yourUsernameInputField']);


 if(isUnique($username))
 {
        // add the user to the database and do anything else you might
       // do on success
 }
 else
 {
         echo 'Your username is already in use, please try again';
 }


}

That is just a basic representation of what it seems like you are trying to do. If your user tables is huge i would recommend not doing 'SELECT *' in order to give you better running time.

brendan2b

Now that I read your post again I guess I am unclear about what youa re trying to accomplish. Let me know if my response wasn't what you were looking for.

djjjozsi

you want that a user if registered, could not register on that computer once?
(not really solvable! )

A user could not register one username more than once in your system?
If it could do that , your system is wrong...

Before you insert into the database, select that username from the server, and make a query, and count if that username is already in your database:


function check_data($content,$table,$field)
{
$sql="SELECT * FROM $table WHERE $field='".mysql_real_escape_string($content)."'";
if (mysql_num_rows(mysql_query($sql))>0)
return(true);
else
return(false);
}

include_once("connect.php");  //connect to the database!

/*....................................form_var......db_Table.........db_field_name...............*/
if(check_data($_POST["username"], "users_table", "username_field")==true)
{
$failes.='username field already has a data You entered!<br>';
$was_failed=1;
}

if(!empty($failes))
print "FAiles: $failes<br>";
else
{
//   here you can put the insert command to the database...
}

vgamemaster

I don't think I was really clear, my registration and login system works fine. The form that I am having problems with is a totally separate form, but you can only submit this form if you are logged in. So once your logged in and submit this form, your username and all of the other information you submitted goes into a database. I want to limit this form to only one submit per user. Does this make sense?

brendan2b

Yes, my misunderstanding. I thought you meant something like that when I re-read your post.

Just simply add a field in your users table called form_submitted or something for your benefit. Make it a varchar of length 1.

When the user correctly submits this form set the value at this field for the user to 1.

Then on the page where you display the form check to see if the value is 1, if it is do not show the form for them to submit, otherwise (meaning the value is nothing, or if you defaulted the field to 0) display the form.

laserlight

vgamemaster wrote:
The form that I am having problems with is a totally separate form, but you can only submit this form if you are logged in. So once your logged in and submit this form, your username and all of the other information you submitted goes into a database. I want to limit this form to only one submit per user. Does this make sense?

If you use a user id (an integer) as the primary key of the users table, then it might be a better idea to store that as the foreign key in this other table. In any case, the solution is to declare this username column (or user id column, as the case may be) as UNIQUE.

You can still make use of the earlier suggestions of checking to see if the username (or user id) already exists, except that the check will be on this second table instead of the users table. If the user has already made a submission, you would then simply inform the user as such. The UNIQUE constraint will ensure that there is no way for users to bypass this check.

brendan2b wrote:
Just simply add a field in your users table called form_submitted or something for your benefit. Make it a varchar of length 1.

I consider that a bad idea - the fact that the user has made a submission is evident in the second table; such a fact has no place in the users table.

brendan2b

Agreed. Makes much more sense to create another table.

vgamemaster

Alright cool I believe I understand what your saying. Just a few noob questions
How do I declare the username column unique?
How do I store the username in another table, without changing the action of the form?

djjjozsi

in your users table, you can make a field, which is an integer type, and has an auto increment property, and primary. With that, you can generate a number, which is identify your user's data. That is called primary key.

If you make a news machine, or a comment box,
you store this number in that another table called foreign key,

for example:
users_table
user_id (primary key)
name
email

news_table
news_id
owner_id ( you put the user's numbers from users_table the user_id)
.....

"without changing the action of the form?"

if you select a user, or has a logged in user, you store in session his/her user_id number. And when you insert a new comment, or news, you put this session variable in another tables.

How to make a field as unique?

ALTER TABLE table_name ADD UNIQUE (
field_name)

run this query in phpmyadmin, or with php.

vgamemaster

in your users table, you can make a field, which is an integer type, and has an auto increment property, and primary. With that, you can generate a number, which is identify your user's data. That is called primary key.

I believe I have that

If you make a news machine, or a comment box,
you store this number in that another table called foreign key,

for example:
users_table
user_id (primary key)
name
email

news_table
news_id
owner_id ( you put the user's numbers from users_table the user_id)

I don't really understand this part, sorry.

And when you insert a new comment, or news, you put this session variable in another tables.

I don't really undertstand this part either, sorry.

ALTER TABLE table_name ADD UNIQUE (
field_name)

Okay I understand how to change it to Unique