Selecting a field with a BIGINT data type in MS Access

[Omnitrix2013]

I have created a MS ACCESS table through python using the pyodbc module, like so:
CREATE TABLE [whole] ( wholeID COUNTER PRIMARY KEY, bin_str VARCHAR(65), twos_comp VARCHAR(65), denary BIGINT, hexadecimal VARCHAR(17) )

Note that the BIGINT data type was used for the denary column (the usual INTEGER datatype is just too small for my conversions), however when I try to query this table, I end up getting a strange format back (despite me checking that everything is saved correctly in the MS Access file as can be seen in image).

Shot of output:

Shot of another output:

Shot of the MS ACCESS database, which has the correct format for the denary field:

The resultant value for the denary column when I use cursor.fetchall() is in a strange format, for instance: what would usually be "747" becomes "˫\x00\x00\x00", what would usually be "700707" becomes "넣\n\x00\x00". Using the INT datatype instead of the BIGINT fixes it.

This is the kind of simple query that I am running:
cursor.execute("SELECT * FROM [whole]")

Including this conversion code didn't change anything:
def decode_bigint(raw_bytes): return int.from_bytes(raw_bytes, byteorder="little") connection.add_output_converter(pyodbc.SQL_BIGINT, decode_bigint)

The ODBC trace:
SQL.LOG

info on ODBC trace

[gordthompson]

Try using connection.add_output_converter(pyodbc.SQL_WCHAR, decode_bigint)

[Omnitrix2013]

That improved things a lot, I used four test cases and three turned out as expected, so there is still some error going on here, I tried changing the byte order to "big" but that didn't work.
See the image of the output and expected:

[gordthompson]

Aha. Try

def decode_bigint(raw_bytes): return int.from_bytes(raw_bytes, byteorder="little", signed=True)

connection.add_output_converter(pyodbc.SQL_WCHAR, decode_bigint)

[v-chojas]

Driver bug.

pythonw.exe -c  6438-ac88	ENTER SQLGetData 
		HSTMT               0x0000023CBEF104C0
		UWORD                        4 
		SWORD                       -8 <SQL_C_WCHAR>
		PTR                 0x0000023CC173B2A0 
		SQLLEN                  4096
		SQLLEN *            0x000000956E9EE2C8

pythonw.exe -c  6438-ac88	EXIT  SQLGetData  with return code 0 (SQL_SUCCESS)
		HSTMT               0x0000023CBEF104C0
		UWORD                        4 
		SWORD                       -8 <SQL_C_WCHAR>
		PTR                 0x0000023CC173B2A0 [       8] "'\ 0\ 0\ 0"
		SQLLEN                  4096
		SQLLEN *            0x000000956E9EE2C8 (8)

pyODBC is requesting the data as a wide string but it appears the driver returns raw 8-byte integer. Of course, even the SQLDescribeCol is wrong as it claims this is an nchar(8) column.