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ORM ¿ò¼ÜÊÇÒ»ÖÖÇ¿Ê¢µÄ¹¤¾ß £¬¿É½«¹¤¾ßÄ£×ÓÓ³Éäµ½¹ØϵÊý¾Ý¿â¡£Ëüʹ¿ª·¢Ö°Ô±¿ÉÒÔÒÔÃæÏò¹¤¾ßµÄ·½·¨ÓëÊý¾Ý¿â½»»¥ £¬´Ó¶ø¼ò»¯ÁËÊý¾Ý¿â±à³Ì¡£

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1. ×°Öà ORM ¿ò¼Ü
Ê×ÏÈ £¬Æ¾Ö¤ÄúµÄ±à³ÌÓïÑÔºÍÊý¾Ý¿âÑ¡ÔñºÏÊ浀 ORM ¿ò¼Ü²¢½«Æä×°Öõ½ÄúµÄÏîÄ¿ÖС£ÀýÈç £¬¹ØÓÚ Python ºÍ PostgreSQL £¬¿ÉÒÔʹÓà SQLAlchemy¡£

2. ½ç˵ģ×ÓÀà
½¨ÉèÓëÊý¾Ý¿â±íÏà¶ÔÓ¦µÄÄ£×ÓÀࡣÿ¸öÄ£×ÓÀàÓ¦°üÀ¨×Ö¶ÎÊôÐÔºÍÄ£×ÓÒªÁì £¬ÒÔÌåÏÖ±íÖеÄÁкÍÐÐΪ¡£ÀýÈ磺

class User:
    id = Column(Integer, primary_key=True)
    name = Column(String(50))
    email = Column(String(50))

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3. ½¨Éè»á»°
ÒªÓëÊý¾Ý¿â½»»¥ £¬ÇëʹÓÿò¼ÜÌṩµÄ»á»°¹¤¾ß¡ £»á»°ÖÎÀíÊý¾Ý¿âÊÂÎñ²¢Ìṩ»á¼ûÊý¾Ý¿âµÄÒªÁì¡£ÀýÈç £¬Ê¹Óà SQLAlchemy µÄʾÀý£º

from sqlalchemy.orm import sessionmaker
Session = sessionmaker()
session = Session()

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4. Ö´ÐÐ CRUD ²Ù×÷
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user = User(name="John", email="john@example.com")
session.add(user)
session.commit()

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users = session.query(User).all()

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user = session.get(User, 1)
user.email = "john.doe@example.com"
session.commit()

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user = session.get(User, 1)
session.delete(user)
session.commit()

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5. ¹Øϵ½¨Ä£
ORM ¿ò¼ÜÔÊÐíÄú½ç˵ģ×ÓÖ®¼äµÄ¹Øϵ £¬ÀýÈçÒ»¶Ô¶à¡¢¶à¶Ô¶àµÈ¡£ÕâʹÄú¿ÉÒÔÇáËɵØÌåÏÖÖØ´óµÄÊý¾ÝÄ£×Ó¡£ÀýÈ磺

class BlogPost:
    id = Column(Integer, primary_key=True)
    title = Column(String(50))

class Comment:
    id = Column(Integer, primary_key=True)
    content = Column(String(50))
    post_id = Column(Integer, ForeignKey('blog_post.id'))

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6. ÅþÁ¬µ½Êý¾Ý¿â
ÔÚÓ¦ÓóÌÐò×îÏÈʱ £¬½¨ÉèÓëÊý¾Ý¿âµÄÅþÁ¬¡£Õâ¿ÉÒÔͨ¹ý¿ò¼ÜÌṩµÄÅþÁ¬³Ø»òÖ±½ÓÅþÁ¬À´Íê³É¡£ÀýÈç £¬Ê¹Óà SQLAlchemy µÄʾÀý£º

engine = create_engine('postgresql://user:password@host:port/database')

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  • ³ä·ÖʹÓà ORM ¿ò¼ÜÌṩµÄ¹¦Ð§ £¬ÀýÈçÅÌÎʹ¹½¨Æ÷ºÍ¹ØϵÖÎÀí¡£

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