Generates the sql for the FROM portion of the query

        :return: the FROM portion of the query
        :rtype: str

def build_from_table(self):
        """
        Generates the sql for the FROM portion of the query

        :return: the FROM portion of the query
        :rtype: str
        """
        table_parts = []

        # get the table sql for each table
        for table in self.tables:
            sql = table.get_sql()
            if len(sql):
                table_parts.append(sql)

        # combine all table sql separated by a comma
        sql = 'FROM {0} '.format(', '.join(table_parts))

        return sql