[Resolved] unique id for pictures uploading

[jonki]

Hi - can anyone spot the obvious mistake in this code?
I am trying to assign an id number to my fotos to make sure that they are not over written. I saw somewhere that suggested I try using $id = mysql_insert_id($conn); but I am not really sure what $id is actually pulling out and if this is indeed a unique number.

Maybe I am totally on the wrong track. I tried using the $id_user from the data base but if I understand things correctly the php form doesn't necessaritly have this data.

$conn=mysql_connect($dbhost, $dbuser, $dbpassword) or die ("Could not connect to database");

mysql_select_db($dbname, $conn) or die ("Could not select $dbname database");

$id = mysql_insert_id($conn);
$newfotoname = $foto_name.$id;

if ($foto_type == "image/pjpeg")
{
copy($foto, "../fotos_coches/".$newfotoname);
}

[Sxooter]

You're doing it in the wrong order. It goes kinda like this:

$conn = mysql_connect(...
$res = mysql_query("insert into table ....
$id = mysql_insert_id($res)

Note that this gets the autoincrement field id number for you. Assuming you don't need to assign it ahead of time, this works fine.

If you just want some kind of unique key that isn't likely to ever repeat, just use varchar and create it in PHP like this:

$key = md5(microtime());

md5 sums tend to not repeat a whole bunch :-)

[jonki]

Fantastic - got it working.

I used the md5(microtime()) suggestion because I needed to do a few checks before I inserted stuff in the data base and therefor couldn't get the id_user early on and I didn't want to be messing around updating the datebase.

The microtime thing - I see what you mean - it looks like someone has closed their eyes gone aìosdyfg23098753io4r on the keyboard.

It does the trick nicely - however is their any way of making this smaller? I remember reading somewhere about taking the first 3 digits - but I can't for the life of me find it now.

Thanks a lot for your help - I really appreciate it.

Jon

[Sxooter]

I'm not sure you can make it smaller and still be reasonable sure it won't ever repeat.

The way I do it in things like postgresql is to declare a sequence and grab from there. In MySQL, you could insert a dummy record, grab the insert_id, then update the row later if you want a shorter number.

But the md5 trick is kinda neat because nobody can tell by looking that this is picture number 13 or picture number 13,301,123

[jonki]

Cheers - that's sorted it out.

I appreciate it.

jon