Date:         Wed, 7 Mar 2001 15:35:18 -0000
Reply-To:     DavidJohnson@HALIFAX.CO.UK
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         David Johnson <DavidJohnson@HALIFAX.CO.UK>
Subject:      LocateN() with Where(), V6.12 TS065 Windows
Content-Type: text/plain; charset=us-ascii

I tracked this through SAS yesterday and their response was that this is a
bug, fixed in V8.  Has anyone else encountered it and proven a solution?


.       Open a data set
.       Apply a where clause
.       Locate a value
.       Use the observation number in a fetch.


Here is some test code, the data set (19 obs) is part of the SAS/Assist
generated data sets.

H = 66.5;
DsId = Open( 'SASUSER.CLASS');
RCWhere = Where( DsId, 'SEX="M"');
NObsNum = LocateN( DsId, VarNum( DsId, 'HEIGHT'), H);
Put 'Test observation number found ' NObsNum =;
NFetch = FetchObs( DsId, NObsNum);
DsId = Close( DsId);


Test first with an H value of 99.  The NObsNum  is 0, which is correct.

Test now for 66.5 and the Where clause commented out.  The NObsNum is 6 for
the first (female) observation.  That is correct.

Now apply the where clause for 'sex=M' and the NObsNum should be 10.  It is
19!


The documentation for LocateN states that the number returned is not the
observation number, because deleted observations, and observations excluded
by a where clause are not counted.

Consequently, the value returned should be the same as FetchObs() expects,
since this honours the where clause.  However, with the where clause
applied, Fetchobs is passed the absolute observation number and fails with
return code -1 which indicates a search past end of data set.

We have two solutions, one of which we are using at present.  I am more
concerned with the consistency of the problem, and need to know if anyone
else has seen this issue and found it to be intermittent.  I am also
interested in other solutions.

The primary solution we have documented is:
.       Release the where clause after the LocateN so FetchObs() functions
on the absolute obs number.  The danger with this approach is that if the
where() clause is SOMETIMES honoured, you'll retrieve the wrong observation
number.


Comments appreciated, please post direct.  I will summarise to the list all
direct postings and the final solution.

Thanks

David

** ##*

David Johnson
> Group Technology & Systems - Mortgages
Business Information Systems Consultant
Collinsons 2nd Floor
Direct Dial : (01422) 39 1360
Ext. : 31360
This message is attributable to the sender and does not necessarily reflect
the view of Halifax Group plc or its subsidiaries.




------------------------------------------------------------------------------
Part of the Halifax Group, Halifax plc, Registered in England No. 2367076.  Registered Office: Trinity Road, Halifax, West Yorkshire HX1 2RG. Represents only the Halifax Financial Services Marketing Group for the purposes of advising on and selling life assurance, pensions and unit trust business.  The Marketing Group is regulated by the Personal Investment Authority.  Switchboard 01422 333333.


 =============================================================================