RE: Update on Access 97 and = NULL

> -----Original Message-----
> From: Mike Mascari [mailto:mascarm@mascari.com]
> 
> Tom Lane wrote:
> > 
> > Mike Mascari <mascarm@mascari.com> writes:
> > > However, I did find this
> > > explanation as to why on the Microsoft Knowledge Base:
> > 
> > > http://support.microsoft.com/support/kb/articles/Q237/9/92.ASP
> > 
> > Interesting.  Apparently, at this point our "Microsoft-compatible"
> > hack is arguably *failing* to be Microsoft-compatible.
> > 
> > The KB article is carefully written to make it sound like the only
> > "foo = NULL" queries out there are mistakes made by users; but wasn't
> > the original issue that Access97 itself would generate a bogus query?
> 

[snip]

> 
> Another possibility, one that Hiroshi suggested and that can be seen in
> the ODBC log files, is that Access 97 is using prepared statements which
> eventually call the ODBC driver's SQLPrepare() function like this:
> 
> SQLPrepare(hstmt, "UPDATE employees SET salary = ? WHERE employeeid =
> ?", SQL_NTS);
> 
> and later, a call to:
> 
> SQLBindParameter(hstmt, 1, SQL_PARAM_INPUT, SQL_C_FLOAT, SQL_REAL, 
>          7, 0, &salary, 0, &salaryind);
> SQLBindParameter(hstmt, 2, SQL_PARAM_INPUT, SQL_C_ULONG, SQL_INTEGER,
> 10, 0,
>                  &employee, 0, &employeeind);
> 
> If the last parameter is set to SQL_NULL_DATA, then that means that the
> last parameter is NULL. That means that the query must be rewritten by
> the driver to "IS NULL" instead of "= NULL". Unfortunately, it *appears*
> our ODBC driver doesn't do that. 

You are right. I'd like to fix it.
When could we translate "= NULL" into "IS NULL" ?
 SELECT statement OK ? SET xxxx = NULL   NG  , xxxx = NULL        NG ? otherwise               OK ?
.....

Comments ?

regards,
Hiroshi Inoue