sqlalchemy 的 Core 方式使用示例

知乎： sqlalchemy 的 core 方式運算元據是一種怎樣的體驗？

答： 爽！

基本步驟如下：

from sqlalchemy import

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

conn = engine.connect()

from sqlalchemy importmetadata

metadata = metadata(engine)

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)
)

# metadata.drop_all()

metadata.create_all()

#

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(), [,,
,,
])

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()

#

繫結資料庫
from sqlalchemy import
create_engine
engine = create_engine('
sqlite:///:memory:
', echo=true)
#連線資料庫
conn =engine.connect()
#元資料
from sqlalchemy import
metadata
metadata =metadata(engine)
#定義表
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))#
建立表# 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(), [,,
,,
])#查詢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()

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