I need a very good reason before using any external library in an attempt to keep the total code base as clean as possible.

It is just too easy to be rushed and bring in a heap of code, so I prefer to use SQL instead of ORM's.

All access to the database is done in a single module and they are wrapped in functions like below

    def get_table_as_list(user_id, cols, tbl, where_clause, params_as_list, conn_str, order_by="1", maxrows='2000'):
        """
        This should be the ONLY place that selects from the database
        """
        db = get_db_conn(conn_str) 
        cur = db.cursor()
        where_clause += ' AND user_id = %s'
        sql = "SELECT " + cols + " FROM " + tbl + " WHERE " + where_clause + " ORDER BY " + order_by + " LIMIT " + maxrows
        params_as_list.append(str(user_id))
        cur.execute(sql, params_as_list)
        res = list(cur.fetchall())
        cur.close()
        db.close()
        return res
        

The database is designed and built first, then in the application the definitions are done like below

    all_tables = [
        {'tbl':'as_note',
         'cols':['id','title','pinned', 'important','content','folder'],
         'col_types':['id','Text','Checkbox','Checkbox', 'Note','Text'],
        },
        {'tbl':'as_task',
        'cols':['id','Title','Pinned', 'Important','Notes','folder','Done'],
        'col_types':['id','Text','Checkbox','Checkbox','Note','Text','Checkbox'],
        }]

So far it is working well, and it is very simple to add new tables to the schema and have them working in the application.