Checking if data exists [loop]

[gamerx]

 

 

Hi,

 

Im trying to generate a random 4- digit code, and then check if it is allready in the database.

 

My current code is below, but im not sure how to make it loop again, if the code exists.

 

Also, im not sure if this is the best way of doing this, maybe someone could suggest something better...

 

 

This is basicly what im trying to do:

1. hash the code

2. check if it exits in the DB

3. if it does, re-generate, and repeat 2., if not, return it

 

 

 

 

function getUniqueHash() {
global $mysql_server, $mysql_user, $mysql_password;

$code = substr(md5(uniqid(rand(), true)), 0, 4);

mysql_connect($mysql_server, $mysql_user, $mysql_password); // connect //
$sql = "SELECT * FROM `$mysql_db`.`short` WHERE `short` = '$code'";
$result = mysql_query($sql);
$results = mysql_numrows($result);
if($results > 0) {
	//GO BACK AND RE-GENERATE CODE AND REPEAT CHECK
} else {
	return $code;
}
mysql_close();
}

 

PasteBin:

http://paste.tgxn.net/?s=9

[wildteen88]

Take a look at this thread

http://www.phpfreaks.com/forums/index.php/topic,307316.0.html

 

It is a similar question to yours. You should be able to modify the function I posted to your needs.

[gamerx]

So, this?

 

function getUniqueHash() {
global $mysql_server, $mysql_user, $mysql_password;
$code = substr(md5(uniqid(rand(), true)), 0, 4);
mysql_connect($mysql_server, $mysql_user, $mysql_password); // connect //
$sql = "SELECT * FROM `$mysql_db`.`short` WHERE `short` = '$code'";
$result = mysql_query($sql);
$results = mysql_numrows($result);
mysql_close();
if($results > 0) {
	return getUniqueHash();
} else {
	return $code;
}
}

[wildteen88]

I wouldn't query mysql for each unique code you generate as this could cause a lot of server load. As you never know if the function will be called once, five times or even a hundred times (depending on how may codes you have).

 

This is why I suggested in the other post to grab all the current codes within the database and add them to an array. I'd then use this array for checking to see if the current code exists. Like so

// a function for getting all codes
function getCodes()
{
    $query = 'SELECT short FROM short';
    $result = mysql_query($query);
    
    $codes = array();
    while(list($code) = mysql_fetch_row($result))
        $codes[] = $code;
    return $codes;
}

// grab the codes array
$codes = getCodes();

// this generates the unique code.
function getUniqueHash(&$codes)
{
$code = substr(md5(uniqid(rand(), true)), 0, 4);
return ((in_array($code, $codes) ? getUniqueHash($codes) : $code );
}

// grab the unique code
$unquie_code = getUniqueHash($codes);

[gamerx]

Am i doing it right?

 

i have this in my "functions"

 

// a function for getting all codes
function getCodes() {
global $mysql_server, $mysql_user, $mysql_password, $mysql_db;
mysql_connect($mysql_server, $mysql_user, $mysql_password); // connect //
$sql = "SELECT * FROM `$mysql_db`.`short`";
$result = mysql_query($sql);
$codes = array();
while(list($code) = mysql_fetch_row($result))
	$codes[] = $code;
mysql_close();
return $codes;
}

// this generates the unique code.
function getUniqueHash($codes) {
$code = substr(md5(uniqid(rand(), true)), 0, 4);
return (in_array($code, $codes) ? getUniqueHash($codes) : $code );
}

 

 

And this when i need to get a (unique) code:

 

// grab the codes array
$codes = getCodes();
// grab the unique code
$content = getUniqueHash($codes);

 

Also, thank you very much for all the help, its really good and i appreciate it

[wildteen88]

Your query is wrong.

	$sql = "SELECT * FROM `$mysql_db`.`short`";

You should only select the field named short. Not all fields otherwise the while loop wont work.

	$sql = "SELECT `short` FROM `$mysql_db`.`short`";

 

With the above fix, you should test it to see if it works.

[gamerx]

that seems to work, but i have no way of testing if it created a unique code

 

Thanks

[wildteen88]

echo $content or insert $content into your database.

[gamerx]

thankyou

[gamerx]

Cant seem to find the edit button, another quick question:

 

how can i edit this to check if $long_url exists in the database, under `$mysql_db`.`long`.

 

so, $long_url exists in `$mysql_db`.`long`, then return the value in `$mysql_db`.`short` for it.

and also still checking for the short code

 

this is what my database looks like: