Update base.py

[OctaOmega]

This change fixes an authentication issue in _build_connection_string() where Windows authentication is implicitly enabled even when it was never configured by the user.

Problem

The current code does this:

trusted_connection = conn_params.get('Trusted_Connection', 'yes')

and later, when USER is not present and no TOKEN is supplied, it unconditionally adds:

cstr_parts['Trusted_Connection'] = trusted_connection

Additionally, in another branch it adds:

cstr_parts['Integrated Security'] = 'SSPI'

For Microsoft SQL Server drivers, both of these effectively enable Windows integrated authentication:

• Trusted_Connection=yes
• Integrated Security=SSPI

As a result, Windows authentication is silently injected into the ODBC connection string by default.

This causes failures in environments that use SQL Server authentication, because the backend forces Windows auth even though the user did not explicitly request it.

Why this is a bug

Not specifying authentication should not be treated as equivalent to enabling Windows authentication.

These are different cases:

• Trusted_Connection=yes or Integrated Security=SSPI
  → Explicit request for Windows authentication

• No authentication parameters provided
  → No preference expressed; backend should not force a mode

By defaulting to Trusted_Connection='yes' and unconditionally adding Integrated Security=SSPI, the current implementation overrides SQL authentication and leads to unexpected connection failures.

Fix

1. Change the default for Trusted_Connection from 'yes' to None
2. Only append Trusted_Connection if it is explicitly provided
3. Avoid adding Integrated Security=SSPI for Microsoft SQL Server drivers unless explicitly required

This ensures the backend does not implicitly force Windows authentication.

Behavior after this change

• If the caller sets Trusted_Connection='yes', it is still added
• If the caller relies on Integrated Security=SSPI via non-Microsoft drivers, legacy behavior is preserved
• If the caller provides USER and PASSWORD, SQL authentication works as expected
• If no authentication method is provided, the backend does not inject one implicitly

Summary

This is a minimal and backward-compatible fix that removes implicit Windows authentication (Trusted_Connection / SSPI) for Microsoft SQL Server drivers, preventing unintended overrides of SQL authentication while preserving explicitly configured behavior.

[OctaOmega]

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[bewithgaurav]

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[bewithgaurav]

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[bewithgaurav]

@OctaOmega - thanks for your contribution!
have run the tests and CI seems to fail for some tests, would it be possible for you to fix them?

[Copilot]

Pull request overview

This PR adjusts how mssql/base.py::_build_connection_string() chooses authentication-related ODBC keywords to avoid implicitly enabling Windows integrated authentication for Microsoft SQL Server drivers when the user did not explicitly request it.

Changes:

• Default Trusted_Connection is changed to None and is only appended when explicitly provided.
• Stops injecting Integrated Security=SSPI for Microsoft drivers (keeps legacy SSPI behavior for non-Microsoft drivers).
• Adds inline comments clarifying the intended authentication behavior.