Date: Tue, 20 Jan 2004 09:54:52 -0800
Reply-To: "Choate, Paul@DDS" <pchoate@DDS.CA.GOV>
Sender: "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From: "Choate, Paul@DDS" <pchoate@DDS.CA.GOV>
Subject: Re: MERGE confusion and disbelief
Doug -
As long as they each have the by variables in sort order you can merge as
many as you want. Note they will overwrite each other where the keys are
the same, so if B0 and W1 have the same by variables on an observation but
W2 and the others don't, B0 will be read, W1 will be read over it, and it
will be output. You should probably read up on merges: BY-Group Processing
in the DATA Step - http://v8doc.sas.com/sashtml/lrcon/z1283274.htm
(User:SAS Pwd:onlinedoc)
You may not know this, but you can also "set" data sets together with a "by"
statement to retain their sorted order, rather than simply concatenating
them and then performing an extra sort.
And be careful to always include your "by" statement, as SAS will perform a
one-to-one merge without warning. I turn on my "options MERGENOBY=warn;".
hth
Paul Choate
DDS Data Extraction
(916) 654-2160
-----Original Message-----
From: Cacialli, Doug [mailto:Doug_Cacialli@URMC.ROCHESTER.EDU]
Sent: Tuesday, January 20, 2004 9:39 AM
To: SAS-L@LISTSERV.UGA.EDU
Subject: MERGE confusion and disbelief
Y'all,
I'm rewriting some non-functioning (or malfunctioning?) code written by a
researcher in my department. In the midst of doing this, I came across:
DATA NANA;
MERGE B0 W1 W2 W3 W4 W5 W5 W6 W7;
BY PATID DRUG;
RUN;
SAS doesn't mouth-off ... it seems to be okay with this. I would've never
attempted this, as I am under the impression that you can't merge more than
two sets in one data step. This has been my impression since I started
using SAS 2.5 years ago.
Have I been living a lie? Can you merge multiple (i.e., more than two) data
sets in one statement like this, or is the result the merge of the first
two? And if that's the case, why isn't SAS all pissed off that I'm
submitting crappy code?! Thanks for the help.
Doug out.
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Doug Cacialli - Data Manager / Data Analyst
Depression Research Laboratory
University of Rochester Medical Center
300 Crittenden Boulevard - Box PSYCH
Rochester, New York 14642
Phone: (585)273-3309 Fax: (585)506-0287
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