Re: gda-sybase: Ongoing developement in cvs

[Brian Bruns <camber ais org>]

On 30 Oct 2000, Rodrigo Moya wrote:

> so, Brian, please enlighten us on this issue (the use of the TDS protocol and
> the implementation of the less possible providers).
> 
> What do you suggest?

Ok, TDS which is the wire-level protocol comes in three basic flavors:

4.2, the oldest in use version supported by both Sybase and Microsoft in
     all dataservers.
5.0, Extensions made by Sybase in ASE 10.x and above.  Adds cursors,
     placeholders and some other stuff.
7.0, Extensions made by MS in SQL Server 7.0.  Adds unicode and long
     char/varchar types (chars with more than 255 bytes)

Sybase OpenClient supports versions 4.2 and 5.0.  Microsofts dblib
supports only 4.2.  Microsofts ODBC and OLE-DB support 4.2 and 7.0.
FreeTDS supports all three protocol versions, with the exception that
unicode is not currently handled but could be added as multibyte charset
support is added.

Some ctlib/dblib programs are likely to break on receiving char types of
more than 255 characters. This is a problem with the program making
assumption about the length and not a limitation of the ctlib or dblib
APIs.  So not a problem here.

On choosing ctlib vs. dblib, either one would do just fine.  The big
question is the trade off between portability back to MS dblib (under
Windows) or support for those items that are new in ctlib.

I would recommend that the current sybase driver should work against MS 
SQL Server almost transparently when using freetds.  Although you may want
to consider an alias or more neutral name so people get the point.

Cheers,

Brian