Specifies the seed value that determines the sequence of values RAND( ) returns.RAND( ) returns the same sequence of random numbers if you use the same seed value for nSeedValue the first time you issue RAND( ) followed by subsequent RAND( ) function calls without nSeedValue.If nSeedValue is negative the first time you issued RAND( ), a seed value from the system clock is used. To achieve the most random sequence of numbers, issue RAND( ) initially with a negative argument and then issue RAND( ) without an argument.If you omit nSeedValue, RAND( ) uses a default seed value of 100,001.
随机数的产生原理与实现http://asp.7i24.com/netcool/laoluo/articles/show_article.asp?Article_ID=24
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