python字符串格式化 f_string

写python的数据库查询时,遇到了这样的语句
按照过去的习惯,会写成

query_like = 'SELECT from_user_id AS from_user_id, target_user_id AS target_user_id, 1 AS level FROM ' \
'user_like WHERE from_user_id = "{}"'.format(user_id)

两个引号丑陋不堪,format写起来也麻烦

发现了pep498

query_like = f'SELECT from_user_id AS from_user_id, target_user_id AS target_user_id, 1 AS level FROM ' \
f'user_like WHERE from_user_id = {user_id!r}'

更好的方式

query_like = f'SELECT from_user_id AS from_user_id, target_user_id AS target_user_id, 1 AS level FROM ' \
f'user_like WHERE from_user_id = {repr(user_id)}'

        engine = create_engine(
            f'mysql+pymysql://{self.user}:{self.passwd}@{self.host}:{self.port}/{self.db}')

不要清晰太多