Insert None with executemany is not supported

[Tweentyy]

Describe the bug

When inserting a column that accepts NULL values with the value None, an error is returned.

Exception message: Exception: RuntimeError: BindParameterArray: Unsupported C type: 99
Stack trace:
[2025-10-02T10:57:39.569Z]   File "/Users/tweenty/Desktop/XXX/test.py", line 31, in insert_data
[2025-10-02T10:57:39.570Z]     cursor.executemany("INSERT INTO TestSQL (TestValue) VALUES (?)", data)
[2025-10-02T10:57:39.570Z]   File "/Users/tweenty/Desktop/XXX/.venv/lib/python3.12/site-packages/mssql_python/cursor.py", line 1682, in executemany
[2025-10-02T10:57:39.570Z]     ret = ddbc_bindings.SQLExecuteMany(
[2025-10-02T10:57:39.570Z] .

To reproduce

Create a table with Nullable column:

CREATE TABLE TestSQL (
      TestValue VARCHAR(50)
)

data = [(None,), (None,)]

cursor.execute("INSERT INTO TestSQL (TestValue) VALUES (?)", data[0]) # Works
cursor.executemany("INSERT INTO TestSQL (TestValue) VALUES (?)", data) # Doesn't work

Expected behavior

Insertion of lines into database.
I have tested with a Decimal column, it's not working so maybe it's a general problem.

Further technical details

Python version: 3.12.10
SQL Server version: SQL Server 2022
Operating system: macOS 26.0.1
mssql_python version: 0.13.0

[gargsaumya]

Thanks for trying out our driver and for sharing the details. We’ll take a look into this issue.
Also, please continue exploring and raising issues, it really helps us improve the driver. Thanks again.

[osuchw]

I've attempted a workaround by using cursor.setinputsizes . It still fails but with

RuntimeError: Unable to cast Python instance of type <class 'str'> to C++ type '?' (#define PYBIND11_DETAILED_ERROR_MESSAGES or compile in debug mode for details)