Question

This is a follow-up question to a question I posted here.

I am using the following code to give users a unique id:

function NewGuid() { 
    $s = strtoupper(uniqid(rand(),true)); 
    $guidText = substr($s,0,8) . '-' . substr($s,8,4) . '-' . substr($s,12,4). '-' . substr($s,16,4). '-' . substr($s,20); return $guidText; 
} 

$Guid = NewGuid();
echo $Guid;

$alphabet = '123456789abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ';

function base_encode($num, $alphabet) { 
    $base_count = strlen($alphabet); 
    $encoded = '';

    while ($num >= $base_count) {
        $div = $num/$base_count;
        $mod = ($num-($base_count*intval($div)));
        $encoded = $alphabet[$mod] . $encoded;
        $num = intval($div);
    }

    if ($num) $encoded = $alphabet[$num] . $encoded;
    return $encoded;    
}

function base_decode($num, $alphabet) { 
    $decoded = 0;
    $multi = 1;

    while (strlen($num) > 0) {
        $digit = $num[strlen($num)-1];
        $decoded += $multi * strpos($alphabet, $digit);
        $multi = $multi * strlen($alphabet);
        $num = substr($num, 0, -1);
    }

    return $decoded;
}

echo base_encode($Guid, $alphabet);

So, if a id that is generated is already in use, i want this code to be able to repeat until a completely new id is generated and entered into the database. IN addition i am new to programming, so please feel free to elaborate 😉

Any thoughts? Thanks.

Answer 1

Super easy.

You have 3 functions.

One – main generate guid function.
Two – Sub generate guid function.
Three – Sub insert guid function.

Sub generate function:
Does the actual generation, returns a guid.

Sub insert function:
Attempts to insert guid into the database. Returns false/null on failure. True/data on success.

Main function:
In a loop:
Call subfunction to get a guid.
Call subfunction to insert in the database where the guid is a unique or primary key.
On failure, restart the loop.
Success exits the loop and returns the guid.

Example:

function GetGuid()
{
    do
    {
        $guid = GenerateGuid();
    } while (!InsertGuid($guid));
    return $guid;
}

function GenerateGuid()
{
    // do your stuff here.
    return $guid;
}

function InsertGuid($guid)
{
    $sql = 'INSERT INTO `guid_table` (`guid`) VALUES ('$guid')';
    $connection = //do sql connect here;
    return // do sql execution here which will return false/null on failure;
}