SQLAlchemy 關聯表刪除實驗

本實驗所用****於官網文件

from sqlalchemy import table, column, integer, string, foreignkey

from sqlalchemy.orm import relationship, backref
from sqlalchemy.ext.declarative import declarative_base
base = declarative_base()
'''關聯表刪除實驗'''
class user(base):
__tablename__ = 'users'
id = column(integer, primary_key=true)
name = column(string)
password = column(string)
addresses = relationship("address", 
back_populates='user', 
cascade="all, delete, delete-orphan")
def __repr__(self):
return "" % ( self.name, self.fullname, self.password)
class address(base):
__tablename__ = 'addresses'
id = column(integer, primary_key=true)
email_address = column(string, nullable=false)
user_id = column(integer, foreignkey('users.id'))
user = relationship("user", 
back_populates="addresses")
def __repr__(self):
return "" % self.email_address
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker
db_connect_string = 'sqlite://' # 'sqlite:///:memory:'
engine = create_engine(db_connect_string, echo=false)
db_session = sessionmaker(bind=engine)
session = db_session()
# 1. 建立表
base.metadata.create_all(engine)
# 2. 插入資料
some_users = [user(id=1, name='張三', password='111111'),
user(id=2, name='李四', password='222222'),
user(id=3, name='王五', password='333333'),
user(id=4, name='趙六', password='444444')]
session.add_all(some_users)
some_addresses = [address(id=1, email_address='[email protected]', user_id=1),
address(id=2, email_address='[email protected]', user_id=1),
address(id=3, email_address='[email protected]', user_id=2),
address(id=4, email_address='[email protected]', user_id=3),
address(id=5, email_address='[email protected]', user_id=4)]
session.add_all(some_addresses)
session.commit()
#關聯表刪除實驗
zhangsan = session.query(user).get(1)
# 刪除!!
del zhangsan.addresses[1]
res = session.query(address).filter(address.email_address.in_(['[email protected]', '[email protected]'])).count()
print(res) # 結果為 1
# 刪除!!
session.delete(zhangsan)
res = session.query(user).filter_by(name='張三').count()
print(res) # 結果為 0
res = session.query(address).filter(address.email_address.in_(['[email protected]', '[email protected]'])).count()
print(res) # 結果為 0

SQLAlchemy 關聯表刪除實驗

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