pymysql-sqlalchemy-orm

sqlalchemy示例代码

多对多外键

场景：一个作者映射多个书籍，一个书籍有多个作者

作者表：
id name email   sex
1  Alex alex@..  M
2  Rail rail@..  W

书籍表：
id name
1  book1
2  book2

作者书籍映射关系表：
id  book_id  anthor_id
1   1           1
2   1           2
3   2           1
【Alex同时参与了两本书的创作】
【book1 有两个作者参与创作】

多对多例子说明

#!/usr/bin/env python
# Author:zhangmingda
''''''
from sqlalchemy import create_engine,ForeignKey,DATE,Table
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String
from sqlalchemy.orm import relationship,sessionmaker
engine = create_engine("mysql+pymysql://zhangmingda:Wyf@1314@120.92.133.227/oldboy_db?charset=utf8",encoding='utf8',echo=False)
'''说明：engine 如果想写入中文，在库名后面加入?charset=utf8 encoding=utf-8 不起作用'''
'''生成基类'''
Base = declarative_base()

book_m2m_author = Table(
    '''此表只存两个表的作者和书名的映射关系'''
    'book_m2m_author',Base.metadata,
    Column('book_id',Integer,ForeignKey('books.id')),
    Column('author_id',Integer,ForeignKey('authors.id'))
)

class Book(Base):
    __tablename__ = 'books' #表的名字
    __table_args__ = {'mysql_charset': 'utf8'}
    id = Column(Integer,primary_key=True)
    name = Column(String(64))
    pub_date = Column(DATE)
    authors = relationship('Author',secondary=book_m2m_author,backref='books') #如何对应第三张表
    def __repr__(self):
        return self.name

class Author(Base):
    __tablename__ = 'authors'
    __table_args__ = {'mysql_charset': 'utf8'} #创建表的字符编码设置
    id = Column(Integer,primary_key=True)
    name = Column(String(32))
    # books = relationship('Book',secondary=book_m2m_author,backref='authors')#如何对应第三张表，作者表或书籍表有一个写了即可
    def __repr__(self):
        return self.name

Base.metadata.create_all(engine)

多对多外键create_table

#!/usr/bin/env python
# Author:zhangmingda
import orm_many_to_many_foreign_key as m2m
from sqlalchemy.orm import sessionmaker

SessionClass = sessionmaker(bind=m2m.engine)
session = SessionClass()
'''作者数据'''
au1 = m2m.Author(name='Alex')
au2 = m2m.Author(name='Rain')
au3 = m2m.Author(name='Jack')
'''书籍数据'''
b1 = m2m.Book(name='跟Alex学Python',pub_date ='2018-09-17' )
b2 = m2m.Book(name='跟Alex学装逼',pub_date ='2018-09-20' )
b3 = m2m.Book(name='跟Alex学把妹',pub_date ='2018-09-22' )
b4 = m2m.Book(name='跟Alex学把妹',pub_date ='2018-09-22' )
'''映射关系'''
b1.authors = [au1,au2,au3]
b2.authors = [au1,au3]
b3.authors = [au2,au3]

# session.add_all([au1,au2,au3,b1,b2,b3])#创建数据
session.commit()

'''============查询:通过书看作者都有谁/通过作者看都创建了啥书===================='''
b1 = session.query(m2m.Book).filter_by(name='跟Alex学Python').first()
print(b1,'的作者是：',b1.authors)

a1 = session.query(m2m.Author).filter_by(name='Alex').first()
print(a1,'创作的书籍有：',a1.books)

'''====删除：多对多删除数据时不用管book_m2m_author　， sqlalchemy会自动帮你把对应的数据删除 通过书删除作者'''
b3 = session.query(m2m.Book).filter_by(name='跟Alex学装逼').first()
print(b3,'的作者有：',b3.authors)
print('删除作者Jack')
jack = session.query(m2m.Author).filter_by(name='Jack').first()
b3.authors.remove(jack)
print(b3,'创作的书籍有：',b3.authors)
session.commit()#提交更改。
'''==============多对多增加数据==========='''
b3 = session.query(m2m.Book).filter_by(name='跟Alex学把妹').first()
print('增加之前，',b3.name,'作者有：',b3.authors)
author  = session.query(m2m.Author).filter_by(name='Alex').first() #找到作者
b3.authors.append(author) #向书籍中append作者
print('增加作者',author.name)
print(b3,'的作者有：',b3.authors)
session.commit()
'''增删改查，第三张表会自动跟着修改。无需多管'''

多对多外键增删改查

多对一外键

#!/usr/bin/env python
# Author:zhangmingda
'''一张表中有两个字段同时外键到另外一个表'''
from sqlalchemy import create_engine,ForeignKey,DATE
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String
from sqlalchemy.orm import relationship,sessionmaker
engine = create_engine("mysql+pymysql://zhangmingda:Wyf@1314@120.92.133.227/oldboy_db?charset=utf8",encoding='utf8',echo=False)
'''生成基类'''
Base = declarative_base()
class Customer(Base):
    '''顾客'''
    __tablename__ = 'customer' #要创建的表名
    __table_args__ = {'mysql_charset':'utf8'}
    id = Column(Integer,primary_key=True)
    name = Column(String(32),nullable=False)
    billing_address_id = Column(Integer,ForeignKey('addresses.id'))
    shipping_address_id = Column(Integer,ForeignKey('addresses.id'))
    '''下面的foregin_keys 指的是通过哪个外键字段去找数据。'''
    billing_address = relationship("Addresses",foreign_keys=[billing_address_id])
    shipping_address = relationship("Addresses",foreign_keys=[shipping_address_id])

class Addresses(Base):
    __tablename__ = 'addresses'
    __table_args__ = {'mysql_charset': 'utf8'}
    id = Column(Integer,primary_key=True)
    street = Column(String(64))
    city = Column(String(64))
    state = Column(String(64))

    def __repr__(self):
        '''被关联的数据正向查询时，return内容作为返回值'''
        return "Address is: state:%s city:%s street:%s " % (self.state,self.city,self.street)
# Base.metadata.create_all(engine)  # 创建表结构

多对一外键create_table

#!/usr/bin/env python
# Author:zhangmingda
from day12.多对一外键到同一张表 import foreginkey_many_orm
from sqlalchemy.orm import sessionmaker
Session_class = sessionmaker(bind=foreginkey_many_orm.engine) #生成数据库连接类(这里的返回值是个类)
session = Session_class() #生成Session实例
'''为addresses表准备数据'''
addr1 = foreginkey_many_orm.Addresses(street='Zhuxinzhuang', city="ChangPing", state="BJ")
addr2 = foreginkey_many_orm.Addresses(street='Wudaokou', city="Haidian", state="BJ")
addr3 = foreginkey_many_orm.Addresses(street='YanJiao', city="Langfang", state="HB")
# session.add_all([addr1,addr2,addr3]) #创建数据
'''为Customer表准备人员数据'''
c1 = foreginkey_many_orm.Customer(name='Alex', billing_address=addr1, shipping_address=addr2)
c2 = foreginkey_many_orm.Customer(name='Rain', billing_address=addr3, shipping_address=addr3)
c3 = foreginkey_many_orm.Customer(name='K', billing_address_id=1, shipping_address_id=2)
c4 = foreginkey_many_orm.Customer(name='Jack', billing_address_id=3, shipping_address_id=3)
# session.add_all([c1,c2,c3,c4]) #c1,c2 和c3,c4两种方式的写法都行，实际应用可能为前者#创建数据

obj = session.query(foreginkey_many_orm.Customer).filter_by(name='Jack').first()
print(obj.name,'billing_address:',obj.billing_address,'\n','shipping_address:',obj.shipping_address)
session.commit()

多对一外键表，创建数据/查询

sqlalchemy

#!/usr/bin/env python
# Author:zhangmingda
'''数据的增删改查'''
from sqlalchemy import create_engine #用来建立连接
from sqlalchemy.ext.declarative import declarative_base #创建表的基类
from sqlalchemy import Column,Integer,String # 表结构数据类型
from sqlalchemy.orm import sessionmaker
'''建立连接'''
engine = create_engine("mysql+pymysql://zhangmingda:Wyf@1314@120.92.133.227/oldboy_db",encoding='utf-8',echo=False)
'''生成基类'''
Base = declarative_base()
'''子类'''
class sub_base(Base):
    __tablename__ = 'user_talbe' #要创建的表名
    id = Column(Integer,primary_key=True)
    username = Column(String(32))
    password = Column(String(64))
'''创建表'''
Base.metadata.create_all(engine) #创建表结构

'''插入数据之 创建session实例'''
Session_class = sessionmaker(bind=engine) #生成数据库连接类(这里的返回值是个类)
Session = Session_class() #生成Session实例
'''准备数据对象'''
data_obj = sub_base(username='Qjj',password='test14413432')#生成创建的数据对象
# Session.add(data_obj) #将数据写入到连接的实例里面
print(data_obj.username,data_obj.id) #还没创建
Session.commit() #提交创建数据
# print(data_obj.username,data_obj.id)

'''查询数据'''
users = Session.query(sub_base).filter_by(username='Qjj')
print(users,'type users',type(users)) #返回所有数据对象
for user in users:
    print(user.id,user.username,user.password)
user_one = Session.query(sub_base).filter_by(username='zhangmingda').first()
print(user_one.id,user_one.username,user_one.password)
'''修改数据'''
user_one.username = 'ZHANGMINGDA'
Session.commit()
'''回滚测试'''
my_user = Session.query(sub_base).filter_by(id=1).first()
my_user.username = 'alex'
new_user = sub_base(username='ALEX',password='12345')
Session.add(new_user)
print('回滚前',Session.query(sub_base).filter(sub_base.username.in_(['LAEX','alex'])).all())
Session.rollback()
print('回滚后',Session.query(sub_base).filter(sub_base.username.in_(['LAEX','alex'])).all())
Session.commit()
'''获取所有数据(每个数据作为元组，多个数据组成元组为元素的列表)'''
print(Session.query(sub_base.id,sub_base.username,sub_base.password).all())

'''多条件查询'''
objs = Session.query(sub_base).filter(sub_base.id>0).filter(sub_base.id<7).all()
print('多条件查询结果')
for obj in objs:
    print(obj.id,obj.username,obj.password)
'''统计个数'''
count = Session.query(sub_base).filter(sub_base.username.like('Zhangmingda')).count()
print('统计符合条件的个数：',count)
'''分组查询'''
from sqlalchemy import func
print('分组查询统计：',Session.query(sub_base.username,func.count(sub_base.username)).group_by(sub_base.username).all())
'''注意这里query 里面的结构：写的是查询出来的结果显示顺序，本例(sub_base.username,func.count(sub_base.username) 为用户名和统计的数字'''
'''删除数据'''
obj_del = Session.query(sub_base).filter(sub_base.id>5).filter(sub_base.username=='Qjj').all()
for d_obj in obj_del:
    Session.delete(d_obj)
Session.commit()

单条数据增删改查

#!/usr/bin/env python
# Author:zhangmingda
'''外键两张表的正反向查询'''
from sqlalchemy import create_engine,ForeignKey,DATE
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String
from sqlalchemy.orm import relationship,sessionmaker
engine = create_engine("mysql+pymysql://zhangmingda:Wyf@1314@120.92.133.227/oldboy_db?charset=utf8",encoding='utf8',echo=False)
'''生成基类'''
Base = declarative_base()
class Students(Base):
    '''学生类'''
    __tablename__ = 'students' #要创建的表名
    __table_args__ = {'mysql_charset':'utf8'}
    id = Column(Integer,primary_key=True)
    name = Column(String(32),nullable=False)
    register_date = Column(DATE,nullable=False)
    def __repr__(self):
        return "<%s name:%s>"%(self.id,self.name)
class Students_Record(Base):
    __tablename__ = 'stu_record'
    __table_args__ = {'mysql_charset': 'utf8'}
    id = Column(Integer,primary_key=True)
    day = Column(Integer,nullable=False)
    status = Column(String(32),nullable=False)
    stu_id = Column(Integer,ForeignKey("students.id"))
    student = relationship('Students',backref = 'record')
    def __repr__(self):
        '''被关联的数据正向查询时，return内容作为返回值'''
        return "record_id:%s %s: day:%s status:%s" % (self.id,self.student.name,self.day,self.status)
Base.metadata.create_all(engine)  # 创建表结构

Session_class = sessionmaker(bind=engine) #生成数据库连接类(这里的返回值是个类)
session = Session_class() #生成Session实例

stu1 = Students(name='Alex',register_date="2018-09-16")
stu2 = Students(name='Jack',register_date='2018-09-17')
stu3 = Students(name='Rain',register_date='2018-09-18')
stu4 = Students(name='Eric',register_date='2018-09-19')
stu5 = Students(name='Qjj',register_date='2018-09-10')
record1 = Students_Record(day=1,status='YES',stu_id=1)
record2 = Students_Record(day=2,status='YES',stu_id=1)
record3 = Students_Record(day=3,status='No',stu_id=1)
record4 = Students_Record(day=4,status='YES',stu_id=2)
record5 = Students_Record(day=1,status='YES',stu_id=3)
# session.add_all([record1,record2,record3,record4,record5])
session.commit()
s1 =  session.query(Students).first() #查询符合条件的单条数据
print(s1)
print(s1.record)#通过外键关系反向调第二张表里面和这个数据有关的所有数据，作为列表返回
for record in s1.record:
    print(record)

record_status = session.query(Students_Record).filter_by(status='YES').all() #找所有没上课的记录，返回列表
for r in record_status: #循环列表，通过上课记录的表没上课的记录反向找学生表里面这个人是谁
    print('%s day %s 没上课'% (r.student.name,r.day))

s2 =  session.query(Students).all() #查询符合条件的所有数据
# print(s2)
# print(s2.record)#通过外键关系反向调第二张表里面和这个数据有关的所有数据，作为列表返回
for s in s2:
    for record in s.record:
        print(record)

外键两张表的正反向查询

#!/usr/bin/env python
# Author:zhangmingda
import sqlalchemy
'''表的创建 查询'''
from sqlalchemy import create_engine,ForeignKey
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String
from sqlalchemy.orm import relationship,sessionmaker
engine = create_engine("mysql+pymysql://zhangmingda:Wyf@1314@120.92.133.227/oldboy_db",encoding='utf-8',echo=False)
'''生成基类'''
Base = declarative_base()
class sub_base(Base):
    __tablename__ = 'user_talbe' #要创建的表名
    id = Column(Integer,primary_key=True)
    username = Column(String(32))
    password = Column(String(64))

class Address(Base):
    __tablename__ = 'addresses'
    id = Column(Integer,primary_key=True)
    email_address = Column(String(32),nullable=False)
    user_id = Column(Integer,ForeignKey('user_talbe.id'))

    user = relationship('sub_base',backref='addresses')
    def __repr__(self):
        '''被关联的数据正向查询时，return内容作为返回值'''
        return "Address(email_address='%s')" % self.email_address

Base.metadata.create_all(engine)  # 创建表结构

Session_class = sessionmaker(bind=engine) #生成数据库连接类(这里的返回值是个类)
Session = Session_class() #生成Session实例
'''在user_talbe表中查询addresses表中的数据'''
obj = Session.query(sub_base).first()
for address in obj.addresses:
    print(address)
'''反向查询'''
add_obj = Session.query(Address).first()
print(add_obj.user.username)

'''连表查询'''
# ret = Session.query(sub_base,Address).filter(sub_base.id == Address.id).all()
# ret = Session.query(sub_base).join(Address).all()
ret = Session.query(sub_base).join(Address,isouter=True).all()
# print(ret)
for obj in ret:
    # print(dir(obj))
    print(obj.addresses,obj.username,obj.password,obj.id)

连表查询

pymysql  read wirte 查询 & 创建数据

#!/usr/bin/env python
# Author:zhangmingda

import pymysql
#读取数据库中的数据
conn = pymysql.connect(host='120.92.133.227',port=3306,user='zhangmingda',passwd='Wyf@1314',db='oldboy_db')
# cursor = conn.cursor() #默认获取的每行数据为元组，多个数据组成嵌套试元组
cursor = conn.cursor(cursor=pymysql.cursors.DictCursor) #每行数据作为一个字典出现，多个数据字典组成列表
cursor.execute("select * from students")
# rown = cursor.fetchmany(3)#只获取三条数据
rowall = cursor.fetchall()

# print('只获取三条数据：',rown)
print('获取全部数据',rowall)
for i in rowall:
    print(i)
conn.commit() #提交保存
cursor.close() #关闭光标
conn.close()#关闭连接

pymysql读取数据

#!/usr/bin/env python
# Author:zhangmingda

import pymysql
#向数据库中写入数据
conn = pymysql.connect(host='120.92.133.227',port=3306,user='zhangmingda',passwd='Wyf@1314',db='oldboy_db')
cursor = conn.cursor()
cursor.execute("delete from students where name='Zahangmiaochen' and 5< id <9;") #删除符合条件的数据from表中
cursor.execute("update students set age = 1 where  id >= %s",(4,)) #更改原有数据
cursor.execute("insert into students (name,age,sex)values(%s,%s,%s)",('Zhangmiaochen',1,'girl'))#插入新数据
cursor.executemany("insert into students (name,age,sex)values(%s,%s,%s)",[('Zhangmiaochen',1,'girl'),('Gongzhu',1,'girl')])#插入多行新数据

conn.commit() #提交保存，否则数据库不会更改生效
cursor.close()
conn.close()
print('自增最新ID',cursor.lastrowid)

pymysql创建数据