Date:         Fri, 20 May 2011 07:21:43 -0400
Reply-To:     "Bian, Haikuo" <HBian@FLQIO.SDPS.ORG>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         "Bian, Haikuo" <HBian@FLQIO.SDPS.ORG>
Subject:      Does SAS really process data one record at a time?
In-Reply-To:  <201105191144.p4JAl4Oo000503@waikiki.cc.uga.edu>
Content-Type: text/plain; charset="us-ascii"

Dear SAS_Lers,

I am sorry if this question has been asked before.

I have been taught many times that SAS deals with data on "one record" basis. This can be seen in the mechanism of PDV among others. What puzzles me is that SAS behavior seems changed after "by" statement. In short, how could SAS determine the value of "FIRST.VARIBLE" or "LAST.VARIBLE" without foreseeing the next record?

Best Regards,
Haikuo
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