Old Wine, New Wineskins:
Why the SQL Procedure WIll Change the Way You Think
Peter Kretzman, McCaw Cellular Communications, Inc.
PernaPI' more tIlon w~h any of the other mkU-languages within
the SAS System.. reasons abound to take a solid look at what
PAoe saL con do fer you. FIrst, unlike til. oth .... (with Ihe
_tion of the macro faolllji). PROC SOL is included with the
base SAS Syat.... and Is tIlus available 10 all SAS u..... on aU
platlonns as of Release 6.06. And. of course, the reason it is
included with the base product is tIlaL like tile macro tacility and
ABSTRACT
Release 6.06 of the SAS system is NOT Just a
"eN
release.
instead, in the increasingly diverse wood of -software
developmenl "sin~ th. SAS Sysl.... Rei ..... 6.00 dramatically
ups the ante. by prm'Iding dIff.....t 'and often bell.,.)
mechantsms to achieve the same results as some common SAS
unlike a specialized subsY$tem such as SAS/lML, ft is a general·
purpose tool,' ooe which can be- used to advantage by f,Nf!fY $AS
programner,
tools such as the MERGE statement
The Sal p",codu",. even 0!'-09 JUGt Q" ordlnruy SAS data
sets, Is one of the most e.KdUng new features of Release 6.06.
Especially consld ....d In tandem with the new obAIly to Index
SAS data sets. PAOe sal immediately jumps Into the category
of Mondal",,! Thin9" 10 Know for Ihe advanced SAS
Secondly. PAOe sal. by .... hodying the "",...ging Structured
Query l.S:nguage standard, represents a G1anCWdiZed way to
fennuiate • query on (in other word•• to retrieve data from)
existlng data. Given the BvalJabAity .of
within the SAS
System, programmers can now migrate qulckly from any of the
numerous database management packages that Qlso employ the
SOL standard as a query language, Although each of these
packages contains extensions to- the SQL standard (and the
SAS System is no exception). there is at least a common ground
now among them. Most importantly. tne availab~ity of saL in ~I
these packages means that thefr metaphor of data
representation is common across them: a relational design,
featuring table. w~h rows and columns. Aside from the us. of
SQl within the SAS System itself. this commona.1ity rnearu;; it Is
lConslderably -easier to conceptualize, and to code, access to
data sacss database platfonns. using the SASJACCESS tools.
Since the SAS Syslein can ship SOL queries d~ectly to external
DBMS packages, it_ r-equlres no
break in stride for the
progJ1m1met to code a piel:O~ of SQl for intemal $AS System use,
oomOO1ed in the same routines as sal code that is Intended to
be shipped elsewhere at runtime,
sal
programmer.
This advanced tutorial compares and contrasts some standard
SAS toots (most notabty, MERGE) with equivalent ways to
achieve the sam. effects using PRoe SaL
Astounding
Improvements ... perfonnance can often be achieved by using
PROO sal instead of more traditional SAS tools.
Concrete examples are provided, along with discussion of
efficiency considerations. After this tutorial. your way of thinking
about a SAS solution to a data combination problem wi. simply
not be the same.
This Morial is intended primarily for _tiVeI)I """erlenced SAS
propmmers who are Interested In the latest tools and
techniques for improving their productivtty,
No previous
knowledge of SOL is • .,,"oned.
The
argumen1fcr using ?ROC SOl1hat will doubUessly have
the greatest weight with current SAS System users. however, is
INTRODUCTION
pme and simple efficiency,
PF\OC SOL provides, at the
very
least. an aHemative (and more efficl-ent) way of achieving the
results of one of the most convnon tools In the -SAS- System: a
Over the years, numerous "'minl--languages" have been added or
grafted On to the basic $AS System: the macro language,
Saeen Control Language (SCI.). the Interaclive Mollix Language
(IMI.). and. most recenHy. the Strucillred OueryLanguage (SOL).
Each of these mlnHanguages exls.ts for a te6s0,.: each.
unfortunately, has lis awn rules. syntax. and set of "gotchas for
the h~ess SAS programmer. The sheer number of these
addltfonaf Pmlnl-languagos" makea It fairly difficult for anyone
anymore simply to daJm that they "know" SAS; instead. one
"knows" the base SAS product, or "knows" each of these
subsystems or subl81lguages indMdually. Few people (myself
included) know aI of the mini-languages now available under the
SAS Syslem.
slmpl. malch-m...go, In many circumstances. PRoe Sal
Can
prOvide data combination results-that would be extremely difficuft
to obtain lIslng conventional SAS System tools.
This introductory pap« is designed to pique your inte.-est, to
whet your appetite. and to make you reaUze the kinds of
situations where you might use FROe saL to great advantage.
n is NOT intended 10 be a thorough investigation into the vast
array of data comblnatlon possib~Wes using sal constructs.
The excellent SAS Guide :to the SOL P«icedure provides
nunteroueJ fine ~ple8 and merits close study. SOL,./I "'whQle
new ball game" within the SAS System, Will demand a significant
efort if you wish to attain we fluency: however, It 15 the goal of
thJs paper to pro\llde a qUicl< "CLJIto Ihe chase" ono show you
the 80% benefit that can be obtained by only 21)% of the work.
U
Given the number of these minHtl"nguages. the burden of proof
for learning any off them has essentiaiy been thrown on the
SAS Sysl.... Itself. Users hove the righl (and the need) to ask:
what.., thE;! tangibl'" benefits of leaming a particular 'subsystem?
What can I do using this subsystem thot will vastly Increase my
productive use ofthe SAS System overaD? Those Issues are the
chief thing to consider w~h "'speet to the "leal kid on Ih. bloc1<,
PRoesaL.
SQl SYNTAX: THE BASICS
The style of this paper will b~ to reveal Sal constFlJm
'lncremen1ally, rather than attempUo show them all at once in a
kind of catalog. fOtmat. However, a basic temp1ate of a bjoin," or
whQt SAS uset'$ refer to as a match-merge,1I is a iJseful startin-g
point for most of the examples in this paper.
H
271
0'
fROM p<Xlion
the SELECT clause. you wi~ get a sepsral.
column lor esch 01 tho.. variables. labeled iden6ca1y. SAS
l)Utput data. 'Sets, of eourse, can CQrmm only roe appes,ranC$ of
any given variable).
PROC SQL FEEDBACK NOPRINT;
CREATE TABLE newtable AS
SELECT ~
FROM data.master AS m#
data. lookup AS 1
WHERE m.key = l.key
M... the variable list is specified. Ihe 1<oyw0l'd fROM appears.
lallowed by a lisl of one or more data sol names. separated by
commas. Each of these data sets may be assigned an arbitrary
alias by uSlrlg the keyword AS. followed by Ihe desired
In
our example, we have asSigned single letter aiases to each of
the two data ..... Asslgnmenl 01 aliases is typically done so
ttlat column names th~ match in the two data sets may be
"qualified," (!hat is, slated unambiguously) during opsatIons
such as processmg of the 'WI-EfI:E clause.
ar,...
ORDER BY idnumber;
The above SQl code is a basic oonstruct that shows how to
combine. 10'
a la'll" labia (-.11IIISIer) wHh a smaller
lookup !able (dataJookup). using the equivalent ofa BY variable.
i1 this case named key. The equivalent conyentional BAS code
would look as follows:
_Ie.
The Tricky Part
Now .here is the 1rIoIIy pari. logically speaking (and " is
nmember lhat this does NOT happ<on physically).
the SOL procedure builds. lable lhal combines each row from
Ihe first lable wHh every row from the second lable. In short, H
nothing further were specified in the query, your rasun would be
fNffI'I possilia oombinaJio.n of the rows. This HaJ combina.1ion"
~ortanllo
DATA newtable;
MERGE data.maater(in=m)
data.lookup(in=l);
BY key;
result is What is referred to as the Cartesian product of the two
IF m AND 1;
tables. If your first table nas eight rows -and your second table
has Ih"'" rows. the Cartesian produOi would conlairl 24 1OW1>:
the first row of the fil"3t table combined. in tum. with .the 1Irst.
second, then third rows of the second tabla, then the second
row of the first 1abIe combined with .... e first. second, then third
rows of th e secon.d table, and $0 01).
RUN;
Wt'$ go through the Sal construct. now and discuss its
implcalions. Fim. Ih. procedure is Irlv01<od wHh • simple PROC
sal cal: think of this as the gateway into the mini-language. It
rums rohtrol tNt!:( to the sal processor, away frotn the
conventional SAS DATA slep and PROC compiler. Saoomly.
is a query language. intended at leaSt. oatensibly to provide
printed ""uMo from eson query. ·It IUm" 0"" of OOU""" Ih.t
much of U!e time you will want to use saL just for its
combinatorial capabiRtie~. rather than to obtain a printed list Clf
its resuits (lhls Is espeolal!y true When you are. combining
lhoosands or mHlons 01 observations!) Hence, more often than
no~ I find mysell using Ihe NOPRINT oplion to tum off the
printing·of the resuHs. In the above exemple. the FEEDBACK
option is also used. ThIs provides extra Information at runtime, in
the SAS log. poJ1alning to how the ",ery was refonnulated by
the sal ",ery optimiz.... and 11Irld H us""'llei ••,,,.lne.
It's actually fairty seldom, of course. 1hat you really want, the
cartesian product of any two lables. The whole concept of a
match-merge, for -example. is bum upon the word Nmalch." That
means you only cafe about CBSes where the key variable agrees
SOL
Note,
in the two tables you are joining. What this means In Cartesian
product terms is thai you only want to ·keep tho rows (in thai
product) where the key ntiable ~n this case; .the variable named
key) malohes. This match is spedlied In the WHERE clause
the SOL query; ou, example 'ealUres Ihe equivalent of Ihe match·
0'
merge, known as an liequijoin'" ail-ce the 'key variab1es must be
equal
the row 10 be kepI In the outputlable.
'0'
Typicaly. you -",oily"' Ihe. ,eferences to Ihe ·key variable by Ihe
alas for one table. -8(J.1ating it to the qualified name of the key
variableforlheothertabill. Typically, there are (N-1) c:onc:fltJ~s
in Ihe WHERE clause for N lables being joined l<Igether. Since
we are logically proceeding from a .labIo (the cartesian product.
that Is) that fealures every possible comblnalion of rows.
not
necessary (unike wHh • match-merge) Ihat Ihe two inpul tables
data.masIer and daIa.lookUp be soned on the I<ey variable.
Noto. however. that the use 01 penods In Ihe WHERE clause Is
."eoilic to the SOL procedUre. and represenl$ use 01 Ihe
n 1he above SQL code. that the syntax is quite -different
n,.
from oonventional SAS System syntax. Most, notabty. only one
semi-<:<>on I, conlairled In the ",ery. 01 the very end lIsIs of
thngs (variables, data sets, etc., have conuna~ sepBlBting the
thing.: in the above _ I e , c"""",," separate Ihe names of
the two data sets that will be lolned.· Finally. aHhough the two
data.e18 Ispeoilled above oonlain penods In th"" names COl the
conventionallonn of ·dbref.dsname:o. the periods In Iho WHERE
clause are something else ildeed, and are discussed further
nalasing" exp~lned above.
finQlIy. iSlnce the input tables are not necessarily SQrted, the
results of the query are not in any particular guaranteed order.
For that reason, you may specif{ an ORDfR BY ,clause to the
query, which serves to place them In the order you desire. Note
thai the variable spedlied in Ihe ORDER BY clause does ",,/
hQ\te to be tha same variable- Q" which the equijoin was
performed. In genenil. PROC Sal gives you • great deal aI
freedom in variable selection: variables listed In your WHERE
dause. for example, do not need to be in the variable fist that
appears Immediately sfterlhe SELECT _emen!.
below.
Ignore the CREATE TABLE statement IQ( now. The meat of most
SQL code is one or more SELECT clauses. A SELECT clause
has two parts, one where you specify what columns you want
and the second wh ..... you specily what data .01> wIM be used.
In the above example, we have specified an asterisk for a
variable list, meaning that we want All variables from each of the
data sets. (NOTE: PROCSOllalres Ihatqun.~ ffyou ore
obtsIning printed ou1p"" 10,
and a variable o'the same
name appears in more than one of -the data sets named In the
_Ie.
272
Piquing Your Interest
PROC SQL NOPRINT,
CREATE TABLE
SELECT ~
NQW that we hav-e g-ottfilO t:h~gh the rudiments of the syntax
Involved in an, equljoin, ,let's look at some timilgs and
oomparison-s, stacking up & conven1lon~ match-merge against
Ihe equivalent SOL construct. Keep in mind that this is, only an
example, and Is not inlended by any means 10 show that SOL is
always beller than a conventional match"""'l!". Oepanding on
your situallon, actual n~ and results may vary ronsidetably.
All Ilmings shown are from runrnng the code on a N-orthgate
486/25 PC, uslng,lhe SAS System under 08/2 (beta lest verslon).
Am. here Is the atandard match....
erg..
FROM
_
carefully.
AS a,
QUIT,
11m.: 3 minutes, 24.44 uconds (1,173 obs. extracted).
In this cas•• RAWOI Is
Whaaaat? This I. the exact ••me rodel Wh .... did .. our time
savlngs g01 In fact. this resuH Is now considerably glNter use
of CPU time than our match merge of one. minute, 44 seconds.
Well. n tum. out th.t Ihis most recenl """"",10 represent. Ih.
same job run without an ,Index having been crealed on the
master dBIB. set: 'lin this case, ra'W'01). The Index, then, allows 1he
SOL query optimizer 10 be con.hlerably more intelligent about
how n processes the query. WIthout that Index. " simply has 10
sort both Inpul dsta oeI$ (thIs h_ens behind the soen.., at
great cost il both CPU time and in disk resources} and proceed
to slog through the dat!>.
Please observe the recorded run
'
DATA MONTH1;
~RGE
rawOl
AS
interest AS w
WHERE a.symbol=Wosymbol
a dsta set containing appro>dmalely 101,000 ob_ons.
INTERESr is a dsla set oontalning approximately 55 occurrences
at the key variable SYMBOL.
result~
RAW01{in~~aw)
INTEREST(in=wanted);
BY SYMBOL;
So no problem, right? Just create 81'1 ildex on all yoor data and
you" be In g,eat shape, right? Wrong. Here', Ihe malch....erge
example, the one that ran in ana mlnute, 44 seconds In our
previous result
IF RAW AND WANTED;
RUN;
Tme: 1 minute, 44.92seoonds (1.173 obs. mraoted)
DATA MONTHl;
HERGE RAW01{in-raw)
INTEREST(in=wanted);
Hmmm.
Not bad for a Fe:
processing over 100,000
observations in only 105 seconds. Now lei'. by H with PROC
SQl:
BY SYMBOL;
IF RAW AND WANTED;
PROC SQL NOPRINT;
CREATE 'TABLE resultl AS
SELECT •
FROM
raw01
WHERE
a.symbol~.symbol
11me: 1 minute, 3 • ..,ond. (1,173 ob •. extracted)
AS a,
interest AS w
Here we go again. Th~ time, the code ran In only 63 seconds,
not 106, So theiast 11m. was w~houl an Index. right? Wrong: in
QUIT; ,
fad. just the -opposite. In a conventional match-merge where the
dala ;s already sorted, Ihe presence of an index "'*'aJtf slows
~ down.
The reason for this is thaI Ihe DATA Slep
processor is not nearly as intel~geJ1t as the SOL query optimizer.
It simply nas to go through each and every observation ~ the
iarlle data set (raW01) and can only check " _ ft ha.
perfomled the combination with Ihe interest data set (via Ih.
. sUbsetting IF statement). If an index is present. it goes out and
Hmmm. Hnvnm. e seconds compared to 105. How would you
feel .bout driving a
thai got you 200 mil... to the gallon? JU.
co,
lessl oslenslbly, H appears lhal PROC SOL, In this instance, can
give . you an order of magnitude better
performan~e
uses
over a
it.
but slnce H.has 10 go through al the data In the large
d .... set anyway. ~ do..", help. In fact. ~ hinders. enough so
thai a 63 second job becomes 67% longer as a result.
. standard match-merge.
Not so fast, buster
Creating an Index
But let's slow down a bit and run a few mere t~ before we get
Now that you've seen the potential benefits of. indexes. howerter.
it would be helpful 1-0' know how 10 create them.. There ate two
ways. to a-eate an index in the SAS System: use -moc
DATASETS or use PROC SQl ttsell,
toe exci1ed. Here's a couple mere examples with slightly
different resuhs:
273
PROC
D~T~SETS
mighty __ In shOO. the downoide Is that every tim. you went
the data In qu..tion. th~ SAS System has to go out and
construct H. But there ate many advantag.. to keeping the
views klstMd of many s u _ or aitema1lv. versions 01 data.
U..... may want s..ersI different version. (literally, views) of the
data, and keeping several physical sets of data kI
synchronlzaUon Is notorioustv <ifficuft. With a view, the data are
always current since data are obtained from a single source and
manlpulnted Intn relevant loons. Andy, views can shield yow
u ..... from the messy datals Involved in large end complex
LIB-WORK;
MODIFY MWOl;
INDEX CREATE SYMBOL,
RUN;
PROC
SQL;
CREATE INDEX (SYMBOL)
ON MWOl(SYHBOL);
QUIT;
merges. To the user, they may not even be aware that a ~en
·data set" Is reaJy • recipe and not a cake aI aI. Once the view
Is coded. you can bo certain that aI of lis users ... be
per10nning the merge corredly. sn"" h Is bolng <lone for them;
RUN;
_0
TIme: 4 minutes. 3.69 seconds
be sure that the users are geWng the most recent
you can
form of your pr1maIy dsta. And, of course •• you want 10 ohange
where and how you have inlptemOl1ted the physical fonn of your
data 'oaae, • Is a good deel eaol... to change a view (whloh Is,
after all, the publio view 01 tho data) than 10 change the data
TImings and PiHalls
Here's- a summary of U1e timings and the pitfals, in chart form:
Operation
Indexed
Non-indexed
MERGE
saL au,""
1:45
1:03
3:24
0:08
structures themsefves.
Invisible Martar
SOL VIeWS, in other words, are a way of providlng USefS with
·invlsible mortar," by which bricks are slapped together and
passed on together. 1ianSparently to U1e view~s user. See my
SUGI 15 pap ... (Kretzman, 1990) on the "Mortar and Bricks"
theme ;, genersl.
Again. !I: is hard to provide hard-and-fast rules of thumb now ,that
the SAS System is so complex (with indexes. multiple platfonns,
etc.). but/or the oImpie kinds 01 equljolns I have outlined here. H
$eat'I1S usually advantageous to use PROC sal and combine it
"With the use of an Index. "that same Indexed data set is going
lot's look at. typical view constructed with PROC saL As with
our other examples, it represents: the equivalent of « match-
merge.
to be used in conventional DATA -steps, however, you may wish
to detele the index. In future SAS releases, there may be a way
to lns'buct the SAS System not to use an Index In a particufar
step. but the", is currenUy no such method avMable.
PROC SQL NOPRINT;
CREATE VIEW thismon AS
Remember .s well that 1il8r<O Is • considerable cost. depending
on the nature af the data. 10 cresting an Index In the first place.
This root muot be weighed agaklat how often (and how) the
data in. question are goilg tD be used.
SELECT
a.symbol, date, high,
low, close, volume
F,ROM
rawOl·
AS a,
interest AS W
WHERE a.symbol=w.symbol
QUIT;
Why Use SQL Views?
M.mng rNay now from the topic of pure efficiency. the rest of
this pap... wia desl with IUlOth ... maiO!' reason I<> u"" SaL: the
&bHHy to creste SOL Views.
You will note that this is virtually the exact same code as I gave
In the tining examples eadier;, this pap .... The key difference,
however, Is lhat CREATE VIEW Is being used, rather than
CREATE TABLE. In short, I'm 1..lng PROC SaL to b"Ud and file
a recipe h ..... not to construct the actuol cake. The recipe, in
this instance, will be a "'work (not pennanent) view called
The SAS System. compOr<Od to most thlrd-generellon languages.
has always had 8 weak point In Us lack of &biHy to "bottle,' as I
Ike to put H. Other then with tho macro language. there haven'
been many constructs in the SAS System 10< Geslgning
something once, then using that something as a buldng block
lor othe< purpo....
Most languages have
procedures; lho SAS System does not. at least within lis own
framowori<. SOL now provi_ SOL views, which are a kind of
"botHilg" tool, not fOf user--wrilten procedures per se. but for
N
1hIomon.
"ser_
let's now examine « case where we use this "View to -do some
work. Note how the reference to thismon appears in a place
where an ordinary data sot relerence could appear. This
exampte also happens I<> be using more SQl. bul ~ wouldn~
have to be. The key point about views Is that they may be used
anywhere you could refer to a SAS data sot (with the exception
thai they may not b.
to In the current release of the SAS
System).
desigr'lill9 IIrl1cipes. 1I Rather than aloMg a particular version of
the data, it is now possible to store Us -recipe, so 10 speak, or
how 1hat version may be constructed. AI the trne you need tbat
v .... lon of the data. you may . . - to ft as H ft actuaUy exist..
employing Its name In SAS prooedures and so on, AI runtime.
the SAS System wil go out. proces. tho recipo. and feed the
resulting r;ake to the procedures that ate referring to ft
II
_en
The polnl of this particular query. _
from Its use of an sal
view. is to obtain • set of stock symbols, ordered by desceodng
average cIosi1g price In the current month. The purpose of the
em.
OJ co""'''' there are pros _
to having a recipe, especially
at Ones when you reaJy want the cake and you w""t the cake
274
view is to obtain only those stocks that ore of interest. as
contained in a SAS data set of l<ey symbols.
changed to AVa, _ l e a were qualified in "'IIKY Instance, and
soon.
The resuKs, as printed, 01 this query look lire Ihe lalowing:
PROC SQL FEEDBACK;
SELECT symbol,
mean(close) AS avgclose
format~7 .2
FROM thismon
GROUP BY symbol
ORDER BY avgclose DESC
SYMBOL
ERICY
IBM
HOT
KSFT
GE
AVGCLOSE
196.16
105.59
62.13
59.40
58.07
QUIT;
Additional Complexities
FlIsI, before we dI"""$o tha role of view. in ",solving this query,
let's examine the addiliaMI sal leature. thst emerge in this
code. An>!, note thst we have specified neither CREATE TABLE
or CREATE VIEW. That m<llllls thal ou, output will be printed
only. Secondly, we have instructed PRae sal to compute a
new variable, which we have told It to call BVgclase." the value of
which wll be the mean of the variable called close. The
AJ;, the reader has no doubt surmised by now, the compleldty in
the SOL procedure far exceeds the swpe of this one paper.
Topics of interest that I have not covered include the following:
GROUP
BY clause tells PAOe SOL over what groups the mean will be
osIoulated (In ohol1. wa W80t one moen for each value 01 Ihe
variable symbo~. Finally, we would like our results sorted in
descending order of Iho newly computed varlalole.
o
o
o
Complexions: outer joins, retlexivejolns, etc.
Subquerio. (within WHERE claus•• , etc.)
Updating data sets using sal
o
o
Set operators (UNION, EXCCPT. INTERSECTION, etc.)
Querying I1lI.Iltipie tables
Oth... arlthmoUc expresslonsln Ihe SELECT c1auso
o
lmagine dOing this same operation using conventional SAS
codel You would need a PROC SUMMARY, then a PROe
SORT, then a PROe PRINT. Sal combine. iii 01 those Ihings
CONCLUSION
Into one.
The SQL Procedure can and should be a vital tool in the arsenal
Note once again that there are syntacticat anomalies to watch
out for. The "DESCH option on the ORDER BY clause, for
example. appears sflor the name of the variable to which it
app~es.
of the accomplished SAS proQrammer.
For pertormance
reasons alone on basic constructs, h is worth taking the time to
learn and 10 learn welt.
unlike how it appears on an ordinary SAS BY :statement
aIs also abbreviated diflerenUy.
Comments, suggestions, and ques1ions are welcome.
author may be reached at the foDowing address:
The fEEDBACK option on the PROC sal statement Hoelf
insllUCIs Ihe PROe sal processor to show us how ~ is
expanding Ihe qJery. In short how H is resolving the ,,,,,!pe that
n has stored in the sal view. Here Is the resuft of that
The
Peter KreIzman
McCaw Celular Communications, Inc.
P.O. Box!l6065
Kiricland. WA 981l3:!-9765
Voice:
(200)8211-1344
FAX:
(200)828·1300
resolution:
SELECT raw. Symbol,
AVG(raw.close) AS avgclose
In addition, the author may be contacted via Internet, USing the
address:
FORMAT=7.2
kretzman@Uwavm.acs.washlngton.edu.
FROM
(SELECT raw. symbol, raw.date,
raw. high, raw~cloae
FIlOM WORK.RAWOl
WORK. INTEREST
WHERE
RAW,
WANTED
ACKNOWLEDGEMENTS
The author wishes to Ihank Ihe felowing people for their
contrlJuUons (wittingly or not) to the thought !hal went into this
peper. Tm F""'ham, Patricia GeroI1d, Gene Hal1. and Paul Kent.
In addition, numerous ideas were obtained from the SAS-L
oon......ce on BITNET.
raw. symbol=wanted. symbol)
GROUP BY raw. symbol
ORDER SY avgclose DEse;
Note how the reference ., the code to thismoo has been
resolved to anoIhBr SELECT clause, one wmch was obtained
from the "recipe" specified In Ihe view. The Sal prooesoo, hao
done scene other "cosmetic- ltIings: nc1e that MEAN was
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276