Python与数据库[2] -> 关系对象映射/ORM -> sqlalchemy 的基本使用示例

sqlalchemy 的基本使用示例

完整代码如下：

  1 from sqlalchemy import create_engine, exc, orm
  2 from sqlalchemy.ext.declarative import declarative_base
  3 from sqlalchemy.sql.schema import Table, ForeignKey, Column
  4 from sqlalchemy.sql.sqltypes import Integer, VARCHAR
  5 from sqlalchemy.dialects.mysql.base import TINYINT
  6 from sqlalchemy.orm import relationship
  7
  8
  9 # declarative_base function will return a class which using active record pattern
 10 # It will combine object opeartion and data operation automatically
 11 Base = declarative_base()
 12
 13 dsn = ‘mysql://root:[email protected]/test_db‘
 14
 15 # Create table based on Base obj
 16 class AccountStore(Base):
 17     __tablename__ = ‘account_store‘
 18     account_id = Column(Integer, primary_key=True)
 19     items = Column(VARCHAR(20))
 20     account = Column(VARCHAR(50))
 21     password = Column(VARCHAR(50))
 22 print(type(AccountStore))
 23 class SqlalchemyActor():
 24     def __init__(self, dsn):
 25         try:
 26             engine = create_engine(dsn)
 27         except ImportError:
 28             raise RuntimeError
 29         engine.connect()
 30
 31         # sessionmaker is a factory obj, generate a Session instance, reload __call__ function
 32         # __call__ function will return a session class each time
 33         Session = orm.sessionmaker(bind=engine)
 34         # use Session() to create a class, and assign it to a attribute
 35         self.session = Session()
 36         # Assign costom table and engine to attribute
 37         self.account = AccountStore
 38         self.engine = engine
 39         # Bind engine and table
 40         # Method one: assign manually one by one
 41         self.account.metadata.bind = engine
 42         # Method two: use reflect to map all/partly Table schema
 43         #Base.metadata.reflect(engine)
 44
 45 ses = SqlalchemyActor(dsn)
 46
 47 def printf(items):
 48     for i in items:
 49         print(i)
 50     print(30*‘-‘)
 51
 52 def printfx(items):
 53     for i in items:
 54         print(i.__dict__)
 55     print(30*‘-‘)
 56
 57
 58 # execute(SQL)
 59 re = ses.session.execute(‘SELECT * FROM account_store‘)
 60 printf(re)
 61 # query(table_name)
 62 # query function similar to Connection.query / Cursor.execute in SQL adaptor
 63 # query(Account) equal to SELECT * FROM acount_store
 64 re = ses.session.query(AccountStore)
 65 print(type(re), re)
 66 printfx(re)
 67
 68 # query(table_name.column_name)
 69 # SELECT items FROM account_store
 70 re = ses.session.query(AccountStore.items)
 71 print(re)
 72 printf(re)
 73
 74 sq = ses.session.query(AccountStore)
 75
 76 # all() / one() / first():
 77 # source code does similar to: lambda x: list(x)
 78 print(type(sq))
 79 print(type(sq.all()))
 80
 81 # filter()
 82 # SELECT * FROM account_store WHERE account_store.items = ‘WeChat‘
 83 re = sq.filter(AccountStore.items==‘WeChat‘)
 84 print(re)
 85 printfx(re)
 86
 87 # filter_by()
 88 # SELECT * FROM account_store WHERE account_store.items = ‘WeChat‘
 89 re = sq.filter_by(items=‘WeChat‘)
 90 print(re)
 91 printfx(re)
 92
 93 # order_by()
 94 # SELECT * FROM account_store ORDER BY account_store.items
 95 re = sq.order_by(AccountStore.items)
 96 print(re)
 97 printfx(re)
 98
 99 # desc()
100 # SELECT * FROM account_store ORDER BY account_store.items DESC
101 re = sq.order_by(AccountStore.items.desc())
102 print(re)
103 printfx(re)
104
105 # limit(): select next 3 values
106 # SELECT * FROM account_store LIMIT 3
107 re = sq.limit(3)
108 print(re)
109 printfx(re)
110
111 # offset(): select from 3rd values
112 # SELECT * FROM table_name OFFSET 2
113 re = sq.offset(2)
114 print(re)
115 printfx(re)
116
117 # select from 3rd and next 3 values
118 re = sq.limit(3).offset(2) # equal to re = sq.offset(2).limit(3)
119 print(re)
120 printfx(re)
121 re = sq[2:5] # equal to re = sq.offset(2).limit(3)
122 print(re)
123 printfx(re)
124
125 # DELETE value
126 re = sq.filter(AccountStore.account_id==8).delete()
127 print(re) # 0 fail, 1 success
128 re = sq.filter(AccountStore.account_id==9).delete()
129 print(re) # 0 fail, 1 success
130 re = sq.filter(AccountStore.account_id==10).delete()
131 print(re) # 0 fail, 1 success
132
133 # INSERT value
134 # Not ORM
135 ses.session.execute(AccountStore.__table__.insert(), {‘items‘: ‘KUBO‘, ‘account‘: ‘STAR‘, ‘password‘: ‘1d2345‘, ‘account_id‘: 10})
136 # Below code is an expression of SQL
137 sql = ses.account.__table__.insert([{‘items‘: ‘Ericsson‘, ‘account‘: ‘EKELIKE‘, ‘password‘: ‘12345‘, ‘account_id‘: 8}, {‘items‘: ‘MOMO‘, ‘account‘: ‘sad‘, ‘password‘: ‘145‘, ‘account_id‘: 9}])
138 ses.session.execute(sql)
139
140 # SELECT value
141 re = sq.get(9)
142 print(re)
143 # Modify value
144 re.password = 1293
145
146 # Count values
147 re = sq.count()
148 print(re)
149
150 ses.session.commit()
151 ses.session.close()

分段分析：

首先对所需要的模块进行导入

from sqlalchemy import create_engine, exc, orm
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.sql.schema import Table, ForeignKey, Column
from sqlalchemy.sql.sqltypes import Integer, VARCHAR
from sqlalchemy.dialects.mysql.base import TINYINT
from sqlalchemy.orm import relationship

随后利用declarative_base()函数创建一个Base类，并且基于Base类创建AccountStore表的各项信息

# declarative_base function will return a class which using active record pattern
# It will combine object opeartion and data operation automatically
Base = declarative_base()

#dsn = ‘mssql+pyodbc://ItpReadOnly:@[email protected]\itp:0/ITP‘
dsn = ‘mysql://root:[email protected]/test_db‘

# Create table based on Base obj
class AccountStore(Base):
    __tablename__ = ‘account_store‘
    account_id = Column(Integer, primary_key=True)
    items = Column(VARCHAR(20))
    account = Column(VARCHAR(50))
    password = Column(VARCHAR(50))

建立起一个sql的执行器，创建一个通信引擎，同时利用orm创建出会话对象，并将会话类与通信引擎进行绑定。通过对会话类的实例化产生一个会话实例。同时手动对表的类进行引擎指向(也可利用reflect进行自动指向)。

class SqlalchemyActor():
    def __init__(self, dsn):
        try:
            engine = create_engine(dsn)
        except ImportError:
            raise RuntimeError
        engine.connect()

        # sessionmaker is a factory obj, generate a Session instance, reload __call__ function
        # __call__ function will return a session class each time
        Session = orm.sessionmaker(bind=engine)
        # use Session() to create a class, and assign it to a attribute
        self.session = Session()
        # Assign costom table and engine to attribute
        self.account = AccountStore
        self.engine = engine
        # Bind engine and table
        # Method one: assign manually one by one
        self.account.metadata.bind = engine
        # Method two: use reflect to map all/partly Table schema
        #Base.metadata.reflect(engine)

接下来对sql执行器进行初始化，并定义两个显示函数用于输出结果。

ses = SqlalchemyActor(dsn)

def printf(items):
    for i in items:
        print(i)
    print(30*‘-‘)

def printfx(items):
    for i in items:
        print(i.__dict__)
    print(30*‘-‘)

完成上述定义后，首先测试session类的execute函数，该函数可以直接执行SQL语句

# execute(SQL)
re = ses.session.execute(‘SELECT * FROM account_store‘)
printf(re)
# query(table_name)
# query function similar to Connection.query / Cursor.execute in SQL adaptor

测试session类的query函数，通过query函数传入表的类，来获取表内的信息，其过程等价于SQL语句中的 SELECT * FROM table_name

# query(Account) equal to SELECT * FROM acount_store
re = ses.session.query(AccountStore)
print(type(re), re)
printfx(re)

对于query函数，若想获取表的其中一列信息，则可以用account_store.item的方式进行，其效果等价于SQL语句的SELECT item FROM account_store

# query(table_name.column_name)
# SELECT items FROM account_store
re = ses.session.query(AccountStore.items)
print(re)
printf(re)

而query函数的返回值通常是一个result类，通过对该类的操作可以获取想要的结果

sq = ses.session.query(AccountStore)

首先是all() / one() / first()函数，分别为获取结果的所有，下一条，第一条项目并返回为list。其中all()函数的源码实现便类似于lambda x: list(x)

# all() / one() / first():
# source code does similar to: lambda x: list(x)
print(type(sq))
print(type(sq.all()))

filter()函数则是一个十分常用的函数，其效果类似于SQL中的WHERE条件子句，通过对filter传入条件语句可以筛选出所需要的结果。类似的filter_by函数则可以以=进行筛选表达

# filter()
# SELECT * FROM account_store WHERE account_store.items = ‘WeChat‘
re = sq.filter(AccountStore.items==‘WeChat‘)
print(re)
printfx(re)

# filter_by()
# SELECT * FROM account_store WHERE account_store.items = ‘WeChat‘
re = sq.filter_by(items=‘WeChat‘)
print(re)
printfx(re)

order_by()函数则类似于SQL中的ORDER BY条件语句，可以对筛选的结果按需求进行顺序排列。当需要倒序排列时，可对排序项目末尾加上.desc()函数

# order_by()
# SELECT * FROM account_store ORDER BY account_store.items
re = sq.order_by(AccountStore.items)
print(re)
printfx(re)

# desc()
# SELECT * FROM account_store ORDER BY account_store.items DESC
re = sq.order_by(AccountStore.items.desc())
print(re)
printfx(re)

limit()函数可以对所需要的结果数量进行获取，等价于SQL中的LIMIT条件语句。将会返回当前结果之后的一定数量结果，数量有limit()传入参数确定

# limit(): select next 3 values
# SELECT * FROM account_store LIMIT 3
re = sq.limit(3)
print(re)
printfx(re)

offset()函数将会对结果进行偏移，等价于SQL的OFFSET语句

# offset(): select from 3rd values
# SELECT * FROM table_name OFFSET 2
re = sq.offset(2)
print(re)
printfx(re)

通常会将limit()函数与offset函数组合进行使用，两个函数的顺序不产生影响，而另外一种获取特定行的方式为切片，这种方式更为简洁明了

# select from 3rd and next 3 values
re = sq.limit(3).offset(2) # equal to re = sq.offset(2).limit(3)
print(re)
printfx(re)
re = sq[2:5] # equal to re = sq.offset(2).limit(3)
print(re)
printfx(re)

delete()函数通常用于从表格中删除相应的行或数据，通过filter()函数加上条件语句将需要删除的项目筛选出来后，加上.delete()来删除该项目，该函数会返回一个结果值，0为删除失败，1为删除成功

# DELETE value
re = sq.filter(AccountStore.account_id==8).delete()
print(re) # 0 fail, 1 success
re = sq.filter(AccountStore.account_id==9).delete()
print(re) # 0 fail, 1 success
re = sq.filter(AccountStore.account_id==10).delete()
print(re) # 0 fail, 1 success

insert()函数，可以采用不基于ORM的方式，直接通过会话实例进行执行。对需要插入的表的类中__table__进行insert()函数调用，execute()函数可以接收两个参数，其中第二个参数为前面函数的传入值，通过这种方式进行值的插入

# INSERT value
# Not ORM
ses.session.execute(AccountStore.__table__.insert(), {‘items‘: ‘KUBO‘, ‘account‘: ‘STAR‘, ‘password‘: ‘1d2345‘, ‘account_id‘: 10})

还有一种插入的代码方式为直接对account.__table__调用insert()函数，而不通过execute，insert函数接收一个列表，列表的每个元素都是字典形式的数据

# Below code is an expression of SQL
sql = ses.account.__table__.insert([{‘items‘: ‘Ericsson‘, ‘account‘: ‘EKELIKE‘, ‘password‘: ‘12345‘, ‘account_id‘: 8}, {‘items‘: ‘MOMO‘, ‘account‘: ‘sad‘, ‘password‘: ‘145‘, ‘account_id‘: 9}])
ses.session.execute(sql)

get()函数可以对结果值的特定指数index位置获取结果

# SELECT value
re = sq.get(9)
print(re)

而若是要对表类的属性，即对表格数据进行修改，由于ORM的存在，只需要对返回结果的属性值进行修改并执行commit即可完成

# Modify value
re.password = 1293

count()函数可以返回对结果数量的计数值

# Count values
re = sq.count()
print(re)

最后，对于存在对数据库产生修改性质的操作，均需要commit进行事务确认才能生效，且在结束操作后需要关闭数据库连接

ses.session.commit()
ses.session.close()

上面的代码运行后输出结果如下，内容较多仅供参考，建议逐个运行进行尝试。

<class ‘sqlalchemy.ext.declarative.api.DeclarativeMeta‘>
(‘WeChat‘, ‘hereisac‘, ‘12345‘, 1)
(‘Qq‘, ‘re32isac‘, ‘123435‘, 2)
(‘Mail‘, ‘re3214ac‘, ‘123435‘, 3)
(‘Gmail‘, ‘re35c‘, ‘123dd5‘, 4)
(‘Google‘, ‘rccc‘, ‘3dd5‘, 5)
(‘MySQL‘, ‘r3c‘, ‘cd5‘, 6)
(‘SQLSERVER‘, ‘r3cdasd‘, ‘d5‘, 7)
(‘Ericsson‘, ‘EKELIKE‘, ‘12345‘, 8)
(‘MOMO‘, ‘sad‘, ‘1293‘, 9)
(‘KUBO‘, ‘STAR‘, ‘1d2345‘, 10)
------------------------------
<class ‘sqlalchemy.orm.query.Query‘> SELECT account_store.account_id AS account_store_account_id, account_store.items AS account_store_items, account_store.account AS account_store_account, account_store.password AS account_store_password
FROM account_store
{‘items‘: ‘WeChat‘, ‘password‘: ‘12345‘, ‘account‘: ‘hereisac‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x00000000048398D0>, ‘account_id‘: 1}
{‘items‘: ‘Qq‘, ‘password‘: ‘123435‘, ‘account‘: ‘re32isac‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004839940>, ‘account_id‘: 2}
{‘items‘: ‘Mail‘, ‘password‘: ‘123435‘, ‘account‘: ‘re3214ac‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x00000000048399B0>, ‘account_id‘: 3}
{‘items‘: ‘Gmail‘, ‘password‘: ‘123dd5‘, ‘account‘: ‘re35c‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004839A58>, ‘account_id‘: 4}
{‘items‘: ‘Google‘, ‘password‘: ‘3dd5‘, ‘account‘: ‘rccc‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004839B00>, ‘account_id‘: 5}
{‘items‘: ‘MySQL‘, ‘password‘: ‘cd5‘, ‘account‘: ‘r3c‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004839BA8>, ‘account_id‘: 6}
{‘items‘: ‘SQLSERVER‘, ‘password‘: ‘d5‘, ‘account‘: ‘r3cdasd‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004839C50>, ‘account_id‘: 7}
{‘items‘: ‘Ericsson‘, ‘password‘: ‘12345‘, ‘account‘: ‘EKELIKE‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004839CF8>, ‘account_id‘: 8}
{‘items‘: ‘MOMO‘, ‘password‘: ‘1293‘, ‘account‘: ‘sad‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004839DA0>, ‘account_id‘: 9}
{‘items‘: ‘KUBO‘, ‘password‘: ‘1d2345‘, ‘account‘: ‘STAR‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004839E48>, ‘account_id‘: 10}
------------------------------
SELECT account_store.items AS account_store_items
FROM account_store
(‘WeChat‘,)
(‘Qq‘,)
(‘Mail‘,)
(‘Gmail‘,)
(‘Google‘,)
(‘MySQL‘,)
(‘SQLSERVER‘,)
(‘Ericsson‘,)
(‘MOMO‘,)
(‘KUBO‘,)
------------------------------
<class ‘sqlalchemy.orm.query.Query‘>
<class ‘list‘>
SELECT account_store.account_id AS account_store_account_id, account_store.items AS account_store_items, account_store.account AS account_store_account, account_store.password AS account_store_password
FROM account_store
WHERE account_store.items = %s
{‘items‘: ‘WeChat‘, ‘password‘: ‘12345‘, ‘account‘: ‘hereisac‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004839278>, ‘account_id‘: 1}
------------------------------
SELECT account_store.account_id AS account_store_account_id, account_store.items AS account_store_items, account_store.account AS account_store_account, account_store.password AS account_store_password
FROM account_store
WHERE account_store.items = %s
{‘items‘: ‘WeChat‘, ‘password‘: ‘12345‘, ‘account‘: ‘hereisac‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x00000000048399B0>, ‘account_id‘: 1}
------------------------------
SELECT account_store.account_id AS account_store_account_id, account_store.items AS account_store_items, account_store.account AS account_store_account, account_store.password AS account_store_password
FROM account_store ORDER BY account_store.items
{‘items‘: ‘Ericsson‘, ‘password‘: ‘12345‘, ‘account‘: ‘EKELIKE‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004858438>, ‘account_id‘: 8}
{‘items‘: ‘Gmail‘, ‘password‘: ‘123dd5‘, ‘account‘: ‘re35c‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x00000000048584A8>, ‘account_id‘: 4}
{‘items‘: ‘Google‘, ‘password‘: ‘3dd5‘, ‘account‘: ‘rccc‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004858518>, ‘account_id‘: 5}
{‘items‘: ‘KUBO‘, ‘password‘: ‘1d2345‘, ‘account‘: ‘STAR‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004858588>, ‘account_id‘: 10}
{‘items‘: ‘Mail‘, ‘password‘: ‘123435‘, ‘account‘: ‘re3214ac‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x00000000048585F8>, ‘account_id‘: 3}
{‘items‘: ‘MOMO‘, ‘password‘: ‘1293‘, ‘account‘: ‘sad‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004858668>, ‘account_id‘: 9}
{‘items‘: ‘MySQL‘, ‘password‘: ‘cd5‘, ‘account‘: ‘r3c‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x00000000048586D8>, ‘account_id‘: 6}
{‘items‘: ‘Qq‘, ‘password‘: ‘123435‘, ‘account‘: ‘re32isac‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004858748>, ‘account_id‘: 2}
{‘items‘: ‘SQLSERVER‘, ‘password‘: ‘d5‘, ‘account‘: ‘r3cdasd‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x00000000048587B8>, ‘account_id‘: 7}
{‘items‘: ‘WeChat‘, ‘password‘: ‘12345‘, ‘account‘: ‘hereisac‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004858828>, ‘account_id‘: 1}
------------------------------
SELECT account_store.account_id AS account_store_account_id, account_store.items AS account_store_items, account_store.account AS account_store_account, account_store.password AS account_store_password
FROM account_store ORDER BY account_store.items DESC
{‘items‘: ‘WeChat‘, ‘password‘: ‘12345‘, ‘account‘: ‘hereisac‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004839390>, ‘account_id‘: 1}
{‘items‘: ‘SQLSERVER‘, ‘password‘: ‘d5‘, ‘account‘: ‘r3cdasd‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x00000000048399B0>, ‘account_id‘: 7}
{‘items‘: ‘Qq‘, ‘password‘: ‘123435‘, ‘account‘: ‘re32isac‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004839EF0>, ‘account_id‘: 2}
{‘items‘: ‘MySQL‘, ‘password‘: ‘cd5‘, ‘account‘: ‘r3c‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x00000000048392B0>, ‘account_id‘: 6}
{‘items‘: ‘MOMO‘, ‘password‘: ‘1293‘, ‘account‘: ‘sad‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004839278>, ‘account_id‘: 9}
{‘items‘: ‘Mail‘, ‘password‘: ‘123435‘, ‘account‘: ‘re3214ac‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004839320>, ‘account_id‘: 3}
{‘items‘: ‘KUBO‘, ‘password‘: ‘1d2345‘, ‘account‘: ‘STAR‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004839470>, ‘account_id‘: 10}
{‘items‘: ‘Google‘, ‘password‘: ‘3dd5‘, ‘account‘: ‘rccc‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004839CF8>, ‘account_id‘: 5}
{‘items‘: ‘Gmail‘, ‘password‘: ‘123dd5‘, ‘account‘: ‘re35c‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004839668>, ‘account_id‘: 4}
{‘items‘: ‘Ericsson‘, ‘password‘: ‘12345‘, ‘account‘: ‘EKELIKE‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004839C88>, ‘account_id‘: 8}
------------------------------
SELECT account_store.account_id AS account_store_account_id, account_store.items AS account_store_items, account_store.account AS account_store_account, account_store.password AS account_store_password
FROM account_store
 LIMIT %s
{‘items‘: ‘WeChat‘, ‘password‘: ‘12345‘, ‘account‘: ‘hereisac‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004839828>, ‘account_id‘: 1}
{‘items‘: ‘Qq‘, ‘password‘: ‘123435‘, ‘account‘: ‘re32isac‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x00000000048397B8>, ‘account_id‘: 2}
{‘items‘: ‘Mail‘, ‘password‘: ‘123435‘, ‘account‘: ‘re3214ac‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004839F28>, ‘account_id‘: 3}
------------------------------
SELECT account_store.account_id AS account_store_account_id, account_store.items AS account_store_items, account_store.account AS account_store_account, account_store.password AS account_store_password
FROM account_store
 LIMIT %s, 18446744073709551615
{‘items‘: ‘Mail‘, ‘password‘: ‘123435‘, ‘account‘: ‘re3214ac‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x00000000048581D0>, ‘account_id‘: 3}
{‘items‘: ‘Gmail‘, ‘password‘: ‘123dd5‘, ‘account‘: ‘re35c‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004858240>, ‘account_id‘: 4}
{‘items‘: ‘Google‘, ‘password‘: ‘3dd5‘, ‘account‘: ‘rccc‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x00000000048582B0>, ‘account_id‘: 5}
{‘items‘: ‘MySQL‘, ‘password‘: ‘cd5‘, ‘account‘: ‘r3c‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004858320>, ‘account_id‘: 6}
{‘items‘: ‘SQLSERVER‘, ‘password‘: ‘d5‘, ‘account‘: ‘r3cdasd‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004858390>, ‘account_id‘: 7}
{‘items‘: ‘Ericsson‘, ‘password‘: ‘12345‘, ‘account‘: ‘EKELIKE‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004858400>, ‘account_id‘: 8}
{‘items‘: ‘MOMO‘, ‘password‘: ‘1293‘, ‘account‘: ‘sad‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004858470>, ‘account_id‘: 9}
{‘items‘: ‘KUBO‘, ‘password‘: ‘1d2345‘, ‘account‘: ‘STAR‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x00000000048584E0>, ‘account_id‘: 10}
------------------------------
SELECT account_store.account_id AS account_store_account_id, account_store.items AS account_store_items, account_store.account AS account_store_account, account_store.password AS account_store_password
FROM account_store
 LIMIT %s, %s
{‘items‘: ‘Mail‘, ‘password‘: ‘123435‘, ‘account‘: ‘re3214ac‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004858208>, ‘account_id‘: 3}
{‘items‘: ‘Gmail‘, ‘password‘: ‘123dd5‘, ‘account‘: ‘re35c‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004858278>, ‘account_id‘: 4}
{‘items‘: ‘Google‘, ‘password‘: ‘3dd5‘, ‘account‘: ‘rccc‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x00000000048582E8>, ‘account_id‘: 5}
------------------------------
[<__main__.AccountStore object at 0x0000000004858390>, <__main__.AccountStore object at 0x0000000004858400>, <__main__.AccountStore object at 0x0000000004858470>]
{‘items‘: ‘Mail‘, ‘password‘: ‘123435‘, ‘account‘: ‘re3214ac‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x00000000048583C8>, ‘account_id‘: 3}
{‘items‘: ‘Gmail‘, ‘password‘: ‘123dd5‘, ‘account‘: ‘re35c‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x0000000004858438>, ‘account_id‘: 4}
{‘items‘: ‘Google‘, ‘password‘: ‘3dd5‘, ‘account‘: ‘rccc‘, ‘_sa_instance_state‘: <sqlalchemy.orm.state.InstanceState object at 0x00000000048584A8>, ‘account_id‘: 5}
------------------------------
1
1
1
<__main__.AccountStore object at 0x0000000004858B38>
10

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原文地址：https://www.cnblogs.com/stacklike/p/8185654.html