Bug: column_value provider uses random() which is not recognised by MS-SQL

[myyong]

Problem

ColumnValueProvider.column_value() in datafaker/providers.py:27–36 selects a random row using:

query = select(orm_class).order_by(functions.random()).limit(1)

SQLAlchemy's functions.random() compiles to random() for all dialects. MS-SQL does not have a random() function and raises an error at runtime:

sqlalchemy.exc.ProgrammingError: ('42000', "[42000] [Microsoft][ODBC Driver 18
for SQL Server][SQL Server]'random' is not a recognized built-in function name.")

The correct MS-SQL equivalents are RAND() (returns a scalar float, usable in ORDER BY) or NEWID() (generates a random GUID, commonly used for random row ordering).

Root cause

functions.random() is not dialect-aware — SQLAlchemy emits random() unconditionally regardless of the connected engine. PostgreSQL and DuckDB both expose a random() function, so this works on those engines, but fails on MS-SQL.

Impact

Any df.py that calls column_value against an MS-SQL source database will fail. This includes OMOP-style schemas where many FK columns are populated via column_value lookups against vocabulary tables (e.g. concept).

Proposed fix

Detect the dialect at runtime inside column_value and substitute the appropriate random expression:

@staticmethod
def column_value(
    db_connection: Connection, orm_class: Any, column_name: str
) -> Any:
    """Return a random value from the column specified."""
    dialect = db_connection.dialect.name
    if dialect == "mssql":
        random_fn = func.newid()
    else:
        random_fn = functions.random()
    query = select(orm_class).order_by(random_fn).limit(1)
    random_row = db_connection.execute(query).first()

    if random_row:
        return getattr(random_row, column_name)
    return None

NEWID() is preferred over RAND() for MS-SQL row ordering because RAND() returns the same value for every row in a single query execution, giving a non-random sort. NEWID() produces a unique value per row and is the standard MS-SQL idiom for ORDER BY random().

Reference

The existing dialect-specific hooks in datafaker/create.py (e.g. remove_mssql_identity, remove_mssql_on_delete_cascade) show the established pattern for handling dialect differences in this codebase.