Error using mssql+pymssl on a Sybase database

[Firass Asad]

Good day! I have an existing setup connecting (doing selects only) to a sybase database and I can successfully use sybase+pyodbc or mssql+pyodbc interchangeably... Now I'm trying to setup and use mssql+pymssql instead, and I am getting an error.

I can successfully connect and query pymssql directly, but it appears that my connection isn't setting server_version_info and it is causing an error on line 1117 of the mssql base dialect file[1].

if I change this line from:

if self.server_version_info[0] not in range(8, 17):

to:

if self.server_version_info and self.server_version_info[0] not in range(8, 17):

then everything works fine.

I'm not sure if you care to support sybase connections using the mssql dialect, but it seems like you wouldn't want emitting a warning cause an uncaught exception.

Thank you,

Firass.

[1] http://www.sqlalchemy.org/trac/browser/lib/sqlalchemy/dialects/mssql/base.py

[Michael Bayer]

On Aug 6, 2012, at 2:58 PM, Firass Asad wrote:

Good day! I have an existing setup connecting (doing selects only) to a sybase database and I can successfully use sybase+pyodbc or mssql+pyodbc interchangeably... Now I'm trying to setup and use mssql+pymssql instead, and I am getting an error.

why  connect mssql+pymssql to sybase?    we support the python-sybase driver directly:  http://python-sybase.sourceforge.net/

I can successfully connect and query pymssql directly, but it appears that my connection isn't setting server_version_info and it is causing an error on line 1117 of the mssql base dialect file[1].

if I change this line from:

if self.server_version_info[0] not in range(8, 17):

to:

if self.server_version_info and self.server_version_info[0] not in range(8, 17):

then everything works fine.

I'm not sure if you care to support sybase connections using the mssql dialect, but it seems like you wouldn't want emitting a warning cause an uncaught exception.

there's probably lots more issues than just this one.   If sybase+pymssql is a use case worth supporting, it would be a new sybase dialect.  However, looking at pymssql http://code.google.com/p/pymssql/ I don't see any mention of "is also sybase compatible".    

The SQLAlchemy project certainly aims to support as many usage models as possible, but supporting DBAPI combinations that aren't supported by the DBAPIs themselves, especially when there are supported alternatives, is not a great place to spend development cycles.

Additional information on your rationale here would be helpful !

[Firass Asad]

My rationale for using mssql+pymssql was because it connects directly using C API instead of ODBC. I could simply connect using the freetds_name instead of installing ODBC drivers.

I tried installing version 0.40 of python-sybase for use with FreeTDS. I was able to connect and run a query using tsql, but not through python-sybase. In both cases, I got a "TDS: unexpected token 73" message; but tsql continued to give me a query prompt, while python-sybase raised a DatabaseError exception.

I am using tds version 4.2 for my connection, so it seems (and I might be wrong here) that pymssql would be compatible with that version of the TDS protocol.

So that is/was my rationale. I was hoping it would just work, and I'm sure you have better places to devote your development cycles :-)

Thank you for your work and your responsiveness.

Sincerely yours,

Firass.

[Michael Bayer]

On Aug 7, 2012, at 7:39 PM, Firass Asad wrote:

My rationale for using mssql+pymssql was because it connects directly using C API instead of ODBC. I could simply connect using the freetds_name instead of installing ODBC drivers.

I tried installing version 0.40 of python-sybase for use with FreeTDS. I was able to connect and run a query using tsql, but not through python-sybase. In both cases, I got a "TDS: unexpected token 73" message; but tsql continued to give me a query prompt, while python-sybase raised a DatabaseError exception.

I am using tds version 4.2 for my connection, so it seems (and I might be wrong here) that pymssql would be compatible with that version of the TDS protocol.

So that is/was my rationale. I was hoping it would just work, and I'm sure you have better places to devote your development cycles :-)

Thank you for your work and your responsiveness.

You might try pinging the python-sybase project - I know it's had a release in recent months so someone is on the case.

Also not sure why you don't alter the TDS version as is appropriate for python-sybase.

Sincerely yours,

Firass.

On Monday, August 6, 2012 12:21:35 PM UTC-7, Michael Bayer wrote:

On Aug 6, 2012, at 2:58 PM, Firass Asad wrote:

Good day! I have an existing setup connecting (doing selects only) to a sybase database and I can successfully use sybase+pyodbc or mssql+pyodbc interchangeably... Now I'm trying to setup and use mssql+pymssql instead, and I am getting an error.

why  connect mssql+pymssql to sybase?    we support the python-sybase driver directly:  http://python-sybase.sourceforge.net/

I can successfully connect and query pymssql directly, but it appears that my connection isn't setting server_version_info and it is causing an error on line 1117 of the mssql base dialect file[1].

if I change this line from:

if self.server_version_info[0] not in range(8, 17):

to:

if self.server_version_info and self.server_version_info[0] not in range(8, 17):

then everything works fine.

I'm not sure if you care to support sybase connections using the mssql dialect, but it seems like you wouldn't want emitting a warning cause an uncaught exception.

there's probably lots more issues than just this one.   If sybase+pymssql is a use case worth supporting, it would be a new sybase dialect.  However, looking at pymssql http://code.google.com/p/pymssql/ I don't see any mention of "is also sybase compatible".    

The SQLAlchemy project certainly aims to support as many usage models as possible, but supporting DBAPI combinations that aren't supported by the DBAPIs themselves, especially when there are supported alternatives, is not a great place to spend development cycles.

Additional information on your rationale here would be helpful !

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[Firass Asad]

I have things working using sybase+pyodbc, but I'll definitely forward my error message to the python-sybase folk.

Thanks again!

Firass.