In the last episode (Jul 15), Arthur Fuller said: > This would be sooo much simpler to solve in MS-SQL, given the function > NewID(), which is guaranteed to return a unique value. I have used this > in a few web sites and it works splendidly; something along the lines of > > SELECT TOP 10 *, NewID() FROM User_Messages ORDER BY NewID > > which is guaranteed to produce a new GUID for each row, and then order by > said values. It is not guaranteed to produce 10 results different than > the previous SELECT, but nevertheless works extremely well on a web site. > > I have Googled this and that but not yet succeeded in finding the > equivalent in the MySQL world. In theory, this should be relatively easy, > since the GUID docs are available, but I'm out of my depth here on how to > write the MySQL equivalent function.
http://dev.mysql.com/doc/refman/5.5/en/miscellaneous-functions.html#function_uuid The UUID() function is that you want. It generates a GUID just like NewID(), but the problem is that a GUID is only guaranteed to be unique, not random: mysql> select uuid() union select uuid() union select uuid(); +--------------------------------------+ | uuid() | +--------------------------------------+ | 11a5cfd1-af13-11e0-80f5-0019b9df7547 | | 11a5d054-af13-11e0-80f5-0019b9df7547 | | 11a5d092-af13-11e0-80f5-0019b9df7547 | +--------------------------------------+ (your output may vary depending on your OS'es preferred type of UUID to generate). You could use md5(uuid()), however, which hashes your unique values to get a nice large pseudorandom number: mysql> select md5(uuid()) union select md5(uuid()) union select md5(uuid()); +----------------------------------+ | md5(uuid()) | +----------------------------------+ | 6faefaf3f7bb9ba0d1e7a44cf6a9b1da | | 740135ab69a1825630aeaf475b39f8b8 | | 5c91a9132ad3e49e098e41d573de8e00 | +----------------------------------+ -- Dan Nelson dnel...@allantgroup.com -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql?unsub=arch...@jab.org
