From your link I read:
Return a random decimal number (no seed value - so it returns a completely random number >= 0 and <1):
Then I read your question about SELECT SQL and do not get how these two SQL commands/functions are related. I certainly found nothing in the SQL documentation that included both.
On top of that, your question about SQLrand "a system" is about "a system" and not the SQL function.
Do you understand that "a system" is not "a function"?