Few things i need help with please!

I want to be able someone to use my signup form.. but if they type an email that already exists in my database i want to be able to send them an error,

i assume i'll be using the "if" command, i'll be using some kind of code like this i take it?:

What code would i put after the if ($_POST[email] = ???????)

and what is the best way to use an error on the same page?

If someone could help i'd be more than happy to give +REP.

Many thanks,
Jamie

Sorry for double post.

Would i possibly assign a variable to the mysql code and then just do:

how would i correctly place the mysql code into the variable though?

Many thanks,
Jamie

The way I normally approach it is this:

$email = mysql_query("SELECT * FROM wherever WHERE email='$email'") or die(mysql_error());
$count = mysql_num_rows($email);

if ($count > 0):

echo "No sir, you cannot register";

else:

echo "Yay! Signed up!";

endif;

As an example:

Some notes:

1. It's completely unnecessary to select all data (SELECT *) unless you absolutely NEED all the information or at least most of it. This is a bad habit to get into. If you're simply doing a validation you only need to SELECT a single field, because the actual validation check isn't performed on any of the retrieved content - thus retrieving it all is pointless and slower.
2. Make sure you sanitise and escape all user input. No user input can be trusted, so use functions like strip_tags and the all important mysql_real_escape_string to make your queries safe.
3. If your database is going to grow fairly large, remember to index the e-mail address field to increase performance.

This is brilliant input thank you gents.

Is there any chance you can give me some specific links to where i can learn how to secure my forms etc please?

Is it just a simple search in google or is there "a best link" for it?

Many thanks,

Jamie

Also is there a simple way of using variables from different files in the same directory without using the "include file.." code?

Thanks.

(btw the +rep isn't workingas of yet. I will add it though.)

Jamie

including and requiring files is the easiest option.

Originally Posted by iamAdam including and requiring files is the easiest option.

So there is no other option to just include variables from another file?

Thanks for the reply Adam,
Jamie

Originally Posted by !LLu$!0N So there is no other option to just include variables from another file? Thanks for the reply Adam, Jamie

That's what effectively (amongst other things) the include function does

http://www.php.net/include