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[AB#38821](https://sqlclientdrivers.visualstudio.com/c6d89619-62de-46a0-8b46-70b92a84d85e/_workitems/edit/38821)

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This pull request adds comprehensive support for the SQL Server `XML`
data type to the Python MSSQL driver, ensuring proper handling for
insertion, retrieval, batching, and streaming of XML data. It also
introduces a suite of tests to verify correct XML behavior, including
edge cases like empty, large, and malformed XML values.

* Added support for the `SQL_SS_XML` data type throughout the driver,
including binding, fetching, and row size calculations, so that XML
columns are handled correctly during data operations.
[[1]](diffhunk://#diff-dde2297345718ec449a14e7dff91b7bb2342b008ecc071f562233646d71144a1R24)
[[2]](diffhunk://#diff-dde2297345718ec449a14e7dff91b7bb2342b008ecc071f562233646d71144a1R2529-R2534)
[[3]](diffhunk://#diff-dde2297345718ec449a14e7dff91b7bb2342b008ecc071f562233646d71144a1R2992)
[[4]](diffhunk://#diff-dde2297345718ec449a14e7dff91b7bb2342b008ecc071f562233646d71144a1R3195-R3198)
[[5]](diffhunk://#diff-dde2297345718ec449a14e7dff91b7bb2342b008ecc071f562233646d71144a1R3412)
* Updated logic in `FetchMany_wrap` and `FetchAll_wrap` to treat XML
columns as LOBs, enabling efficient streaming for large XML values.
[[1]](diffhunk://#diff-dde2297345718ec449a14e7dff91b7bb2342b008ecc071f562233646d71144a1L3504-R3517)
[[2]](diffhunk://#diff-dde2297345718ec449a14e7dff91b7bb2342b008ecc071f562233646d71144a1L3626-R3639)

* Added multiple tests in `tests/test_004_cursor.py` to verify XML
handling, including basic insert/fetch, empty/null values, large XML
streaming, batch inserts, and error handling for malformed XML input.
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