Preventing Duplicates

hybernate20

I apologize if this is somewhere in these forums, but I tried to look for it first.

I'm doing something where I need to enter ID numbers, but I don't want the same one twice. Furthermore, I would like for the page to give an error if this happens.

I don't entirely know how to do this, but I've read around and found stuff like

mysql_query("SELECT COUNT(*) FROM <table> WHERE <column>"). This is great and all, but if I try to save that value to a variable, like

$counter=mysql_query("SELECT COUNT(*) FROM <table> WHERE <column>"),
I don't get a number, such as 0 or 1 or anything that I want, I get a Resource #3 or something along those lines. All I want is to be able to check the database against the ID given in a form to see if it is there. If it is, I wanna go to a page that says "This ID is already in use, please try again", otherwise, go to a page that says "successful." I know how to do all of this except to able to check for the duplicate.

If I were to get a number, then I could just do an if($counter=="0")........for my other pages.

Sorry the post was so long! I'm just very frustrated right now. Any help would be awesome! Thanks!

tomhath

After you execute the query you need to fetch the results.

http://us2.php.net/manual/en/function.mysql-fetch-array.php

Roger_Ramjet

The other thing you need to do is to change the way you code with mysql query.

$query = "SELECT COUNT(*) FROM <table> WHERE <column>";
$result = mysql_query($query) or die ($query . '<br />' . mysql_error());

That way if you get an error you can see what the sql really was as well as the error you got. Makes bedugging so much easier.

If you do the sensible thing and move up to PHP ver 5 then you can forget all about mysql_query etc and start using PDO prepared statements. The advantages of ver 5 are many but just being able to use PDO would make it worthwhile on its own.