'Executes the sql and returns a pandas dataframe
:param sql: the sql statement to be executed (str) or a list of
sql statements to execute
:type sql: str or list
:param parameters: The parameters to render the SQL query with.
:type parameters: mapping or iterable'

def get_pandas_df(self, sql, parameters=None):

    if (sys.version_info[0] < 3):
        sql = sql.encode('utf-8')
    import pandas.io.sql as psql
    with closing(self.get_conn()) as conn:
        return psql.read_sql(sql, con=conn, params=parameters)
