*execute sql query using the sdss API*

        **Key Arguments:**
            # -

        **Return:**
            - None

        .. todo::

def _execute_sql_query(
            self):
        """
        *execute sql query using the sdss API*

        **Key Arguments:**
            # -

        **Return:**
            - None

        .. todo::

        """
        self.log.info('starting the ``_execute_sql_query`` method')

        # generate the api call url
        params = urllib.urlencode({'cmd': self.sqlQuery, 'format': "json"})
        # grab the results
        results = urllib.urlopen(self.sdssUrl + '?%s' % params)

        # report any errors
        ofp = sys.stdout
        results = results.read()
        if results.startswith("ERROR"):  # SQL Statement Error -> stderr
            ofp = sys.stderr
            ofp.write(string.rstrip(line) + os.linesep)

        # clean up the json response so it can be parsed
        results = results.replace(
            ": ,", ': "NULL",')
        regex = re.compile(r'"photoz_err"\:\s*(\n\s*})')
        newString = regex.sub('"photoz_err": "NULL"\g<1>', results)
        results = newString

        # parse the json results
        results = json.loads(results)[0]
        self.results = results["Rows"]

        self.log.info('completed the ``_execute_sql_query`` method')
        return