Have you thought of using a UUID: http://dev.mysql.com/doc/refman/5.0/en/miscellaneous-functions.html#func tion_uuid While not real pretty, it would save you the extra "SELECT". You could also just MD5(UUID()) to make it a bit 'smaller', or some other mechanizm. Even something as simple as MD5(UNIX_TIME()) might be fine enough resolution/granularity for your needs, depending on how many simultaneous "INSERT"s you expect. Honestly, I would use a little reverse logic, and not do the select first (which is a wasted query as you have more chance of success if your 'random' pool is big/unique enough), but rather _assume_ it will INSERT, and then handle the case you get a "DUPLICATE KEY" issue (i.e. a failure. "ERROR 1062 (23000): Duplicate entry '1' for key 1", so you can check: This is rough pseudo code, but you get the idea... $key = UUID(); While (!success) { $sth = mysql_query("insert into () values ()"); if (!$sth || mysql_error() == '1062') { //pick a new key and loop around. continue; } $success = true; } > -----Original Message----- > From: blueboy [mailto:ross@xxxxxxxxxxxxx] > Sent: Wednesday, June 06, 2007 7:40 AM > To: php-general@xxxxxxxxxxxxx > Subject: customer ids > > Hi, > > I want to create random customer ids. I have an auto > incremented coulumn but > I would rather have a 6-8 digit/letter id randomly generated > that can be > used as a unique identifier across 3 tables. Does anyone have > a algorithm to > generate such a string and can you give the odds against 2 > duplicate stings > being generated? > > I know this is a strange ask. > > > R. > > -- > PHP General Mailing List (http://www.php.net/) > To unsubscribe, visit: http://www.php.net/unsub.php > > -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
