SNOW-735220: update documentation of pd_writer (#1642)

src/snowflake/connector/pandas_tools.py

@@ -460,13 +460,26 @@ def pd_writer(
 ) -> None:
     """This is a wrapper on top of write_pandas to make it compatible with to_sql method in pandas.
 
+        Notes:
+            Please note that when column names in the pandas DataFrame are consist of strictly lower case letters, column names need to
+            be enquoted, otherwise `ProgrammingError` will be raised.
+
+            This is because `snowflake-sqlalchemy` does not enquote lower case column names when creating the table, but `pd_writer` enquotes the columns by default.
+            the copy into command looks for enquoted column names.
+
+            Future improvements will be made in the snowflake-sqlalchemy library.
+
         Example usage:
             import pandas as pd
             from snowflake.connector.pandas_tools import pd_writer
 
             sf_connector_version_df = pd.DataFrame([('snowflake-connector-python', '1.0')], columns=['NAME', 'NEWEST_VERSION'])
             sf_connector_version_df.to_sql('driver_versions', engine, index=False, method=pd_writer)
 
+            # when the column names are consist of only lower case letters, enquote the column names
+            sf_connector_version_df = pd.DataFrame([('snowflake-connector-python', '1.0')], columns=['"name"', '"newest_version"'])
+            sf_connector_version_df.to_sql('driver_versions', engine, index=False, method=pd_writer)
+
     Args:
         table: Pandas package's table object.
         conn: SQLAlchemy engine object to talk to Snowflake.