I have upgraded to MS SQL Server 7.0 and can no

DBA > Job Interview Questions > Sybase Interview Questions and Answers

More DBA job interview questions and answers at http://dba.fyicenter.com/Interview-Questions/

(Continued from previous question...)

I have upgraded to MS SQL Server 7.0 and can no longer connect from Sybase's isql.

With SQL Server 7.0, Microsoft changed the TDS protocol; they themselves call it "TDS 7.0". They didn't actually change it in any fundamental way. They added some tokens and stretched the use of others.

Microsoft's marketing sometimes utters stupidities like "ODBC is the native protocol for SQL Server", but ODBC isn't a protocol. If you dig, you'll find some references to TDS in their technical docs, a sort of grudging admission that TDS still undergirds everything.

What Microsoft dropped was TDS 5.0 support, which is the version Sybase developed after they licensed SQL Server to Microsoft. There is a patch that will provide that support for SQL Server 7.0, but no such patch exists for SQL Server 2000. You can still connect to 2000 with TDS 4.2, which is what is used by pre-System 10 tools and by Microsoft's current isql command line tool.

Actually, to say MS SQL ever supported 5.0 is a bit misguided. The extent of support was basically, it would accept a TDS 5.0 login packet and then tell the client to fall back to 4.2. This was basically because the 4.2 and 5.0 login packets were largely the same. I frankly would avoid even attempting to send 5.0 to MS SQL as it will likely re-break at some point in the future (like when they remove 4.2 support down the road).

The following table gives you an idea of what is supported.

+---------------------------------------------------------------+
|     | MS SQL       |     Sybase ASE         |    Sybase ASA   |
+---------------------------------------------------------------+
|ver  |6.5 |7.0 |2000| <10.x     | >11.0      |<5.5.03|5.5*|>6.0|
+-----+----+----+----+-----------+------------+-------+----+----+
| 4.2 | X  | X  |  X |    X      |      X     |       |    |    |
| 5.0 |    |    |    |           |      X     |       | X  | X  |
| 7.0 |    | X  |  X |           |            |       |    |    |
| 8.0 |    |    |  X |           |            |       |    |    |
+-----+----+----+----+-----------+------------+-------+----+----+

* Sybase ASA 5.5 requires 5.5.03 or better with the OpenServer Gateway 
(OSG).

(Continued on next question...)