Re: comparing rows

Magnus Hagander wrote:
> 
> Can somebody enlighten me as to *when* Access creates a query that has
> "=null" in it?
> 
> I just tried to reproduce it, and I failed.
> 

The problem appears (just from a quick look at the mail archive)
to manifest itself when Access generates queries to handle Forms
processing. Below is a sample issue that people had when using
Access 97 w/PostgreSQL:

------------------------------------------------------
From: mmw@paradise.net.nz 
To: pgsql-interfaces@postgresql.org 
Subject: Access ODBC worries 
Date: Thu, 12 Aug 1999 16:44:41 +1200 (NZST) 

Hi All

I have been battling with a problem now for days. I have a linked
form in Access 97 to linked tables to a PGSQL backend via ODBC.
The code works well, but after the form has been on the screen
for about 20 minutes idling or doing something (makes no
difference) then all hell breaks loose.  The computer tries to
requery the form data from the backend in a very strange way. 
The odbc log file output at the bottom of this message explains
the problem in greater detail.

...

<ODBC log follows>

...

------------------------------------------------------------
hdbc=91652364, stmt=91555964, result=0
manual_result=0, prepare=0, internal=0
bindings=0, bindings_allocated=0
parameters=92605260, parameters_allocated=1
statement_type=0, statement='SELECT "Toplevel time
recordal"."oid" FROM "Toplevel time
recordal" WHERE ("File link" =  ? ) ORDER BY "Startdate"  DESC '
stmt_with_params='SELECT "Toplevel time recordal"."oid" FROM
"Toplevel time recordal"
WHERE ("File link" =  NULL ) ORDER BY "Startdate"  DESC '
data_at_exec=-1, current_exec_param=-1, put_data=0
currTuple=-1, current_col=-1, lobj_fd=-1
maxRows=0, rowset_size=1, keyset_size=0, cursor_type=0,
scroll_concurrency=1
cursor_name='SQL_CUR0575087C'
----------------QResult Info -------------------------------
CONN ERROR: func=SC_execute, desc='', errnum=110, errmsg='ERROR: 
parser: parse error
at or near "null"'

------------------------------------------------------

I'll attempt to provide an easily repeatable operation, but the
problem *does* exist in Access 97.

Mike Mascari