MySQL thread-safe get_or_create function

# 这里用到了sqlalchemy
def get_or_create(param1):
    try:
        db.session.execute('LOCK TABLES table_name WRITE;')
        a = TableName.query.filter_by(param1=param1).first()
        if a is None:
            a = TableName(param1)
            db.session.add(a)
            db.session.commit()
        db.session.execute('UNLOCK TABLES;')
        return a
    except Exception, e:
        logging.error("xxx.py get_or_create exception:" + str(e))
    return None

def increase(uid):
    try:
        User.query.filter_by(userid=uid).update({"money":User.money + 1})
        db.session.commit()
    except Exception, e:
        logging.error("xxx.py increase exception:" + str(e))
    return None