sqlalchemy 的 Core 方式使用示例

1. 绑定数据库

from sqlalchemy import create_engine

engine = create_engine('sqlite:///:memory:', echo=True)

2. 连接数据库

conn = engine.connect()

3. 元数据

from sqlalchemy import MetaData

metadata = MetaData(engine)

4. 定义表

from sqlalchemy import Table, Column, Integer, String, ForeignKey, Sequence

users = Table('users', metadata,
Column('id', Integer, Sequence('user_id_seq'), primary_key=True),
Column('name', String),
Column('fullname', String),
)

addresses = Table('addresses', metadata,
Column('id', Integer, primary_key=True),
Column('user_id', None, ForeignKey('users.id')),
Column('email_address', String, nullable=False)
)

5. 创建表

# metadata.drop_all()
metadata.create_all()

6. 插入

# 方式一
ins = users.insert().values(name='jack', fullname='Jack Jones')
conn.execute(ins)

# 方式二
conn.execute(users.insert(), id=2, name='wendy', fullname='Wendy Williams')

# 方式三
conn.execute(addresses.insert(), [
{'user_id': 1, 'email_address' : 'jack@yahoo.com'},
{'user_id': 1, 'email_address' : 'jack@msn.com'},
{'user_id': 2, 'email_address' : 'www@www.org'},
{'user_id': 2, 'email_address' : 'wendy@aol.com'},
])

7. 查询

from sqlalchemy.sql import select

for row in conn.execute(select([users])):
print("name:", row[users.c.name], "; fullname:", row[users.c.fullname])

for row in conn.execute(select([users, addresses])):
print(row)

for row in conn.execute(select([users, addresses]).where(users.c.id == addresses.c.user_id)):
print(row)

from sqlalchemy.sql import and_, or_, not_
s = select([(users.c.fullname +
", " + addresses.c.email_address).
label('title')]).\
where(
and_(
users.c.id == addresses.c.user_id,
users.c.name.between('m', 'z'),
or_(
addresses.c.email_address.like('%@aol.com'),
addresses.c.email_address.like('%@msn.com')
)
)
)
conn.execute(s).fetchall()

8. 完整代码

# 绑定数据库
from sqlalchemy import create_engine
engine = create_engine('sqlite:///:memory:', echo=True)

# 连接数据库
conn = engine.connect()

# 元数据
from sqlalchemy import MetaData
metadata = MetaData(engine)

# 定义表
from sqlalchemy import Table, Column, Integer, String, ForeignKey, Sequence
users = Table('users', metadata,
Column('id', Integer, Sequence('user_id_seq'), primary_key=True),
Column('name', String),
Column('fullname', String),
)

addresses = Table('addresses', metadata,
Column('id', Integer, primary_key=True),
Column('user_id', None, ForeignKey('users.id')),
Column('email_address', String, nullable=False)
)

# 创建表
# metadata.drop_all()
metadata.create_all()

# 插入
# 方式一
ins = users.insert().values(name='jack', fullname='Jack Jones')
result = conn.execute(ins)
# 方式二
conn.execute(users.insert(), id=2, name='wendy', fullname='Wendy Williams')
# 方式三
conn.execute(addresses.insert(), [
{'user_id': 1, 'email_address' : 'jack@yahoo.com'},
{'user_id': 1, 'email_address' : 'jack@msn.com'},
{'user_id': 2, 'email_address' : 'www@www.org'},
{'user_id': 2, 'email_address' : 'wendy@aol.com'},
])

# 查询
from sqlalchemy.sql import select

for row in conn.execute(select([users])):
print("name:", row[users.c.name], "; fullname:", row[users.c.fullname])

for row in conn.execute(select([users, addresses])):
print(row)

for row in conn.execute(select([users, addresses]).where(users.c.id == addresses.c.user_id)):
print(row)

from sqlalchemy.sql import and_, or_, not_

s = select([(users.c.fullname +
", " + addresses.c.email_address).
label('title')]).\
where(
and_(
users.c.id == addresses.c.user_id,
users.c.name.between('m', 'z'),
or_(
addresses.c.email_address.like('%@aol.com'),
addresses.c.email_address.like('%@msn.com')
)
)
)
conn.execute(s).fetchall()