FIX: bind executemany money-range Decimals as SQL_NUMERIC

[VyrnSynx (vyrnsynx)]

Work Item / Issue Reference

GitHub Issue: #745

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Summary

executemany auto-detect still used the MONEY/SMALLMONEY-range VARCHAR shortcut after #742 fixed execute(). A money-range Decimal compared against a smaller numeric column could still overflow on that path.

This change binds auto-detected Decimal columns as SQL_NUMERIC with a batch-wide precision/scale (values still go through the existing SQL_C_CHAR string conversion). The setinputsizes DECIMAL/NUMERIC string path (GH-503) and mixed-sign VARCHAR sizing (GH-557) are left alone.

Fixes #745

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[Copilot]

🟡 Changes recommended

The new batch precision/scale path needs stricter validation and the current executemany numeric override still conflates numeric precision with string buffer sizing in a way that can produce invalid SQL Server precision (>38) for some Decimal shapes.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

This PR fixes the remaining executemany() auto-detection path where MONEY/SMALLMONEY-range Decimal values could still be bound as SQL_VARCHAR, causing SQL Server to overflow when comparing against smaller numeric/decimal columns. The change aligns executemany() with the already-fixed execute() behavior by binding auto-detected Decimal columns as SQL_NUMERIC using a batch-wide precision/scale, while still sending values as SQL_C_CHAR strings.

Changes:

• Update executemany() auto-detect to bind Decimal columns as SQL_NUMERIC (skipping the MONEY-range VARCHAR shortcut) and compute a batch-wide (precision, scale).
• Add unit/integration tests covering the GH-745 overflow regression and mixed-sign batch behavior.
• Document the behavior change in the changelog and update explanatory test/module docs.

File summaries

File	Description
mssql_python/cursor.py	Adds batch-wide Decimal precision/scale derivation and applies it to executemany() auto-detect numeric binding.
tests/test_020_money_smallmoney.py	Adds DB integration coverage for GH-745 (no overflow on executemany comparisons; mixed-sign batch still works).
tests/test_004_cursor.py	Adds unit tests for batch precision/scale derivation and verifies executemany binds money-range Decimals as SQL_NUMERIC.
CHANGELOG.md	Records GH-745 fix and clarifies setinputsizes behavior remains unchanged.

Review details

Suppressed comments (1)

mssql_python/cursor.py:2729

• executemany’s SQL_NUMERIC/SQL_DECIMAL override reuses ParamInfo.columnSize both as the numeric precision (passed as cbColDef to SQLBindParameter) and as the max SQL_C_CHAR buffer length. Setting columnSize to max_decimal_len (which includes sign and decimal point) can push the declared numeric precision above SQL Server’s max 38 (e.g., scale-38 values format to 40 chars), causing bind failures unrelated to the actual numeric precision/scale. Consider decoupling numeric precision from string buffer sizing (e.g., compute buffer sizes from actual encoded string lengths in BindParameterArray when SQLType is NUMERIC/DECIMAL but keep cbColDef=precision<=38).

                    # Ensure columnSize also accommodates the longest string form
                    # (mixed-sign batches, GH-557).
                    if max_decimal_len > paraminfo.columnSize:
                        paraminfo.columnSize = max_decimal_len

• Files reviewed: 4/4 changed files
• Comments generated: 1
• Review effort level: Lite

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