Might it be simpler, since you're assuming the presence of PHP anyway, to just read your entire result set into an array and then shuffle() it and then pick off the top however-many entries? Of course, that won't be very memory-efficient for particularly large data sets... --- Mark Roedel | "Blessed is he who has learned to laugh Systems Programmer | at himself, for he shall never cease LeTourneau University | to be entertained." Longview, Texas, USA | -- John Powell > -----Original Message----- > From: Gerard Samuel [mailto:gsam@trini0.org] > Sent: Tuesday, June 24, 2003 11:19 AM > To: Doug Thompson > Cc: Becoming Digital; PHP-DB > Subject: Re: Rand() Emulation > > > Im probably not making myself clear. > Ultimately, my goal is to emulate mysql's -> > SELECT * FROM TABLE ORDER BY RAND() LIMIT (X) > > for other databases that do not support RAND(). So using > variations of php's rand(), wouldn't make sense, as it only > picks one value out of a range of values, that are numerical > in nature. > > But here is an idea, that Im thinking about, but haven't > gotten to the code as yet. > 1. In the tables that I want random values from, create a "rand" > column, that contains incremental numerical values for each row. > 2. select the the maximum number from the rand column. > 3. Assume that there are no gaps between 0 and this max number. > 4. Create an array of numbers with values between 0 and max number. > 5. Use array_rand() to "randomly" choose (x) values from the array > created in step 4. (I may choose maybe a 1 or 2 values more than > whats required, just in case of gaps between 0 and max number in > step 3). > 6. Use these randomly choosen values to select from the database as > random rows. > > So hopefully its a bit clearer what Im striving for. > To me the idea above would work, but it hinges on if that > rand column, doesn't have gaps. > If you see room for improvement, or have another idea, or if > Im talking > gibberish then by all means. > > Thanks. > > Doug Thompson wrote: > > >An incredible interpretation of > > > ><quote> > >If called without the optional min, max arguments rand() > returns a pseudo-random value between 0 and RAND_MAX. If you > want a random number between 5 and 15 (inclusive), for > example, use rand (5, 15). > ></quote> > > > >Doug > > > > > -- > PHP Database Mailing List (http://www.php.net/) > To unsubscribe, visit: http://www.php.net/unsub.php > > -- PHP Database Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
