CRecordset.Open() - Driver does not support dynaset

Ramachandra Rao -- chandu@ampersand.soft.net
Saturday, November 23, 1996

Environment: Visual C++ 4.0, Win95

Hi
	I am trying to open a CRecordset of type dynaset. But I get the message
"Driver does not support dynaset". The comments in the  MFC code tell
that, dynasets require odbc32.dll of version 2.0 . But the version of
the odbc32.dll that comes with VC++ 4.0 is  2.50 . Then what could the
problem be?
I am trying to connect to SQLServer 6.5 . Is there any workaround for
this problem or should I get a third party driver that supports
dynasets.?

Thanks
Chandu

---

David J. Straley -- djs@cnj.digex.net
Sunday, November 24, 1996

[Mini-digest: 2 responses]

On Sat, 23 Nov 1996 00:23:45 +0530, you wrote:

>Environment: Visual C++ 4.0, Win95
>
>Hi
>	I am trying to open a CRecordset of type dynaset. But I get the message
>"Driver does not support dynaset". The comments in the  MFC code tell
>that, dynasets require odbc32.dll of version 2.0 . But the version of
>the odbc32.dll that comes with VC++ 4.0 is  2.50 . Then what could the
>problem be?
>I am trying to connect to SQLServer 6.5 .=20

Make sure you create a separate CDatabase object and then do an Open()
on it, passing FALSE for the parameter for ODBC Cursor Lib, which is
TRUE by default.  You gotta get rid of that cursor lib for dynasets to
work.  Hang in there.  :)

	Regards,


                        Dave  Straley

            David J. Straley, Software Developer =20
           Windows * Windows NT * Unix/X Windows
                  -- djs@cnj.digex.net --
-----From: Strhan Mojmir 

Hi Chandu!

To use dynaset, you need:
1) switch-off usage of cursor library e.g. in CDatabase::Open() set
(last) parameter bUseCursorLib to FALSE
2) switch-on cursor type DYNASET e.g. in CRecordset::Open() specify
nOpenType as CRecordset::dynaset
3) if you call stored procedure, ensure that it is "simple SP" -> SP
which contains one and only one
   SELECT statement

These steps should enable usage of DYNASET to you. But I want to warn
you:
if you want to program application which should also work with other
servers than Microsoft SQL Server 6.5,
it is a bad practice to hardcode type of cursor in your code, because
DYNASET will perhaps not be available
on other SQL servers and/or drivers - for example Intersolv's ODBC
driver for Microsoft SQL Server does not
support DYNASETs.

So if you need portable application, you should program yourself class
COdbcWorkspace, which should deal with:
-HDBC (CDatabase) mapping -> how many simultaneous HDBCs supports server
and/or driver?
-HSTMT (CRecordset) mapping -> how many simultaneous HSTMTs per HDBC
supports server and/or driver
-cursor type mapping -> which cursor types supports server and/or driver
-stored procedures mappings -> which type of SP (simple versus complex)
can you use with which cursor type

If you program such a class, you will be able to port your application
to other servers in few hours, because you will
only need to port (enhance) COdbcWorkspace, not the rest of code.

You cannot expect to see any code from me, because this code is rated
"TOP SECRET" in our company.
You also cannot expect to see such a class in next releases of MFC,
because Microsoft is quite
happy with hardcoded cursor types, because this means that you can only
use Microsoft SQL Server :-)

Hope this helps.

Mojmir Strhan
strhan_m@simultan.ch

---

Luke Stephens -- luker@tfs.net
Sunday, November 24, 1996

SQL Server 6.0/6.5 comes with a new driver that supports dynasets. So far,
the driver has worked for me.

What kind of query are you doing?  Did you know that the driver requires a
unique index for dynasets to work with SQL Server?  I think there is an
article about this in the MSDN.

Hope this helps
Luke Stephens
luker@tfs.net

----------
> From: Ramachandra Rao. S 
> To: 'MFC Mailing List' 
> Subject: CRecordset.Open() - Driver does not support dynaset
> Date: Friday, November 22, 1996 12:53 PM
> 
> Environment: Visual C++ 4.0, Win95
> 
> Hi
> 	I am trying to open a CRecordset of type dynaset. But I get the message
> "Driver does not support dynaset". The comments in the  MFC code tell
> that, dynasets require odbc32.dll of version 2.0 . But the version of
> the odbc32.dll that comes with VC++ 4.0 is  2.50 . Then what could the
> problem be?
> I am trying to connect to SQLServer 6.5 . Is there any workaround for
> this problem or should I get a third party driver that supports
> dynasets.?
> 
> Thanks
> Chandu

---

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