March 2022
Intermediate to advanced
522 pages
13h 52m
Chinese
Content preview from Python语言及其应用（第2版）
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16.5.5 PostgreSQL
PostgreSQL
是一款功能完善的开源关系数据库。在很多方面，它的确比
MySQL
更高级。
表
16-4
列出了访问其所需的
Python
驱动程序。
表16-4：PostgreSQL驱动程序
名称
Pypi
包 导入为 注意事项
psycopg2 psycopg2 psycopg2
需要
PostgreSQL
客户端工具
pg_config
py-postgresql py-postgresql postgresql
最流行的驱动程序是
psycopg2
，但安装时要求有
PostgreSQL
客户端库。
16.5.6 SQLAlchemy
SQL
在所有的关系数据库中并不完全相同，
DB-API
也只能帮你这么多了。每种数据库都
实现了反映自身特性和设计理念的特定
方言
。许多库尝试以这样或那样的方式来弥补这些
差异。最流行的跨数据库
Python
库是
SQLAlchemy
。
SQLAlchemy
并不在标准库内，但其声名在外，用户众多。可以使用下列命令进行安装。
$
pip install sqlalchemy
SQLAlchemy
可应用于多个层面。
•
最底层管理数据库连接池、执行
SQL
命令并返回执行结果。这个层面最接近于
DB-API
。
•
再往上一层是
SQL
表达式语言
（
SQL
expression language
），其允许你以更
Python
化的
方式表达
SQL
查询。
•
最高层是对象关系模型（
objec
t relational model
），其会使用
SQL
表达式语言，将应用
代码和关系数据结构结合起来。 ...
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