fix: report temporal fractional precision

[iamlinjunhong]

Problem

Python datetime.datetime(2024, 2, 29, 23, 59, 59, 123456) bound by pyodbc 5.3.0 to a MatrixOne DATETIME(6) or TIMESTAMP(6) column is stored as .100000, losing five fractional-second digits.

Direct SQL literals preserve .123456, and a direct ODBC bind with SQL_TIMESTAMP_STRUCT.fraction=123456000, ColumnSize=26, and DecimalDigits=6 also preserves .123456.

Root cause

pyodbc calls SQLGetTypeInfo(SQL_TYPE_TIMESTAMP) once per connection and computes its datetime bind precision as COLUMN_SIZE - 20. The driver advertised:

• datetime: COLUMN_SIZE=21, MINIMUM_SCALE=0, MAXIMUM_SCALE=0
• timestamp: COLUMN_SIZE=14, MINIMUM_SCALE=0, MAXIMUM_SCALE=0

pyodbc therefore truncated the Python fraction to one digit before calling SQLBindParameter. MatrixOne supports DATETIME(6) and TIMESTAMP(6), whose full display width is 26.

Fix

Advertise COLUMN_SIZE=26, MINIMUM_SCALE=0, and MAXIMUM_SCALE=6 for both datetime and timestamp.

Add an end-to-end mo_odbc_deep regression that calls SQLGetTypeInfo(SQL_TYPE_TIMESTAMP), finds both rows, and asserts all three fields.

Reproduction

import datetime
import pyodbc

cn = pyodbc.connect(CONNECTION_STRING, autocommit=True)
cur = cn.cursor()
cur.execute("create table t(id int primary key, dt datetime(6), ts timestamp(6))")
value = datetime.datetime(2024, 2, 29, 23, 59, 59, 123456)
cur.execute("insert into t values (?,?,?)", 1, value, value)
print(cur.execute("select cast(dt as varchar), cast(ts as varchar) from t").fetchone())

Before / after

• Before (8f1ca365): timestamp_type_info=FAIL; pyodbc stored .100000.
• After (c0ea21ea): timestamp_type_info=PASS; raw timestamp fraction bind, SQLForeignKeys, timeout, and cancel remain PASS.

The direct verifier loads the built DLL itself and does not depend on replacing the installed driver.

Test scope

• Windows x64 CMake build: Unicode and ANSI drivers + mo_odbc_deep: PASS
• git diff --check: PASS
• Direct DLL before/after SQLGetTypeInfo comparison: expected FAIL / PASS
• Direct DLL SQL_TIMESTAMP_STRUCT fraction round trip: PASS
• Direct DLL SQLForeignKeysW: PASS
• Direct DLL query timeout (HYT00): PASS
• Direct DLL cancel (HY008): PASS

Test server: MatrixOne 592ad2190a90e063e3877059f4018427a10a4998.

Note: Python datetime.time microseconds are a separate portability limitation because standard SQL_TIME_STRUCT has no fraction field. Binding the TIME value as an ISO string preserves microseconds and is not changed by this PR.