[Python-sybase-misc] Unknown data format when selecting len(convert(varbinary(MAX)...))

[Deron M. <der...@gm...>]

I have pysybase 0.38 connecting to a SQL Server database.

There is a table with a blob/image column, say:

  table A
     a_id   int(10)  not null primary key;
     a_blob   image(2147483647)  null;

Trying to get the length of the image, I found this works:

   select datalength(a_blob) from A where a_id = 12345;

but the following supposedly equivalent SQL will raise a TypeError

   select len(convert(varbinary(MAX), a_blob)) from A where a_id = 12345;


The above SQL though works at a SQL prompt...using freetds,
but not with the python-sybase interface.


Digging down in Sybase.py the error is coming from the
_extract_row() function, where it is trying to reference "buf[n]"

In this case:
   n = 0
   buf = <DataBufType object at 0xb7acd980>
   buf.datatype = 30
   buf.format = 0
   buf[n] = ..... TypeError: unknown data format

Any ideas?
-- 
Deron Meranda