Someguy (6/9/2009)
Mike C.Thank you for your answer to a slightly lazy question - Yes, I should have simply run the query SELECT Rand() and pushed the start button several times and I would have seen that for single runs, Rand defaults to 'no seed required.'
Although in terms of this article, it seems like the generation of multiple rows, each with its own random number is not an outrageous requirement in the programming world. This is especially true considering the fact that SQL is meant to call sets as well as individual results. And yes, I understand that most systems don't produce truly random numbers but hard-coded sequences, so 'random' keywords in programming do are not really random, but practically useful for most instances.
Maybe a better way to word the question would be, if Microsoft can create a keyword like NewID that produces a new result for each new row, why can't they either do the same for Rand() or gives us another keyword (considering that at this point there are mountains of code with back-flips that will get messed up if Rand() were changed,or assuming that Rand() may fit some current standard for SQL)? That way, we wouldn't have to use the currently existing random generator functionality from NewID to make Rand() work the way you would otherwise expect it to work.
Incidentally, another interesting site is Random.org, which generates random numbers based on atmospheric noise.
RAND() probably won't be changed in it's behavior for the exact reason you mention -- backwards-compatibility. A new keyword/function could be a possibility, but they probably won't anytime soon. Unless you have a compelling reason--such as with the introduction of CRYPT_GEN_RANDOM for cryptographic random numbers--there's not much call for randomness in the database. Most uses I've seen for random number generation in SQL boil down to two scenarios: (1) retrieving random rows from a result set, and (2) generating random data to store in the database for testing. Both can be done from the client side or the server-side, with the current functionality, and both tend to be one-off development, testing and troubleshooting requirements as opposed to daily production requirements.
I believe it's Schneier's book where he recommends using subatomic particle decay to generate random numbers 🙂