zoukankan      html  css  js  c++  java

  • SQLAlchemy 增删改查 一对一 多对多

    首先要导入SQLAIchemy模块

    from sqlalchemy.ect.declaative import  declarative_base

    创建orm基类

    Base = declarative_base()

    创建orm对象

    class User(Base):
    __tablename__ = "user"
    
    id = Column(Integer,primary_key=True,autoincrement=True)
    name = Column(String(32),index=True)

    创建数据库链接

    from sqlalchemy import create_engine
ngine = create_engine("mysql+pymysql://root:pwd@127.0.0.1:3306/user?charset=utf8")
备注：pwd表示密码，如果数据库属性中没有密码的话可以忽略，user是数据库名
    # 数据库链接创建完成
    # 去数据库中创建与User所对应的数据库表
    # 去engine数据库中创建继承Base类所对应的数据表
    Base.metadata.create_all(engine)

    #############################################################################################################################

    添加数据

    首先打开数据库链接

    from sqlalchemy import create_engine
engine = create_engine("mysql+pymysql://root:pwd@127.0.0.1:3306/user?charset=utf8")

    创建会话窗口---打开数据库链接

    from sqlalchemy.orm import  sessionmaker

    创建会话

    Session = sessionmaker(engine)

    打开会话窗口

    db_session = Session()

    添加单条数据

    user_obj=  User(name="ywb")
db_session.add(user_obj)

    添加多条数据

    db_session.add_all([
    User(name="Alex"),
    User(name="Wusir"),
    User(name="Yuan")

])

    开始执行操作

       db_session.commit()

    执行完成之后关闭执行命令

    db_session.close()

    查询数据

     1 # 创建会话窗口
 2 from sqlalchemy.orm import sessionmaker
 3 from creat_table import engine,User
 4 
 5 Session = sessionmaker(engine)
 6 db_session = Session()
 7 
 8 
 9 # 简单的查询语句
10 user_list = db_session.query(User).all()
11 for row in user_list:
12     print(row.id,row.name)
13 
14 # 单条查询
15 user = db_session.query(User).first()
16 print(user.id,user.name)
17 
18 
19 # 带条件的查询
20 user_list = db_session.query(User).filter(User.id==4).all()
21 print(user_list[0].id,user_list[0].name)
22 
23 user = db_session.query(User).filter_by(id=3).first()
24 print(user.id,user.name)
25 
26 user_list = db_session.query(User).filter(User.id>=2).all()
27 for row in user_list:
28     print(row.id,row.name)
29 
30 
31 # 查询sql语句(拓展)
32 sql = db_session.query(User).filter(User.id>=2)
33 print(sql)
    查询数据

    修改更新数据

     1 #修改数据
 2 
 3 
 4 # 建立会话
 5 from sqlalchemy.orm import sessionmaker
 6 # 导入链接数据库的模块
 7 from creat_table import engine,User
 8 # 开始创建会话
 9 Session = sessionmaker(engine)
10 # 开启会话
11 db_session = Session()
12 
13 # 开始修改数据
14 res = db_session.query(User).filter(User.name=="ybw").update({"name":"哈哈哈"})
15 print(res)
16 
17 db_session.commit()
18 db_session.close()
    修改更新数据

    删除数据

     1 #删除数据
 2 
 3 
 4 from sqlalchemy.orm import sessionmaker
 5 from creat_table import engine,User
 6 
 7 Session = sessionmaker(engine)
 8 db_session = Session()
 9 
10 
11 # 删除
12 
13 res = db_session.query(User).filter(User.id ==4 ).delete()
14 print(res)
15 
16 db_session.commit()
17 db_session.close()
    删除数据

    建立一对多：的ForeignKey关系实现的增删改查

    创建数据库

     1 #一对多操作
 2 
 3 
 4 from sqlalchemy.ext.declarative import declarative_base
 5 
 6 Base = declarative_base()
 7 
 8 from sqlalchemy import Column,String,Integer,ForeignKey
 9 from sqlalchemy.orm import relationship
10 
11 class Student(Base):
12     __tablename__ = "student"
13     id = Column(Integer,primary_key=True)
14     name = Column(String(32))
15     school_id = Column(Integer,ForeignKey("school.id"))
16 
17     stu2sch = relationship("School",backref = "sch2stu")
18 
19 class School(Base):
20     __tablename__ = "school"
21     id = Column(Integer,primary_key=True)
22     name = Column(String(32))
23 
24 
25 from sqlalchemy import create_engine
26 engine = create_engine("mysql+pymysql://root:@127.0.0.1:3306/day127?charset=utf8")
27 Base.metadata.create_all(engine)
    创建数据库

    添加数据

     1 #   添加数据
 2 
 3 
 4 from sqlalchemy.orm import sessionmaker
 5 from creat_table_ForeignKey import engine,Student,School
 6 
 7 Session = sessionmaker(engine)
 8 db_session = Session()
 9 
10 ## 添加数据   原始方法
11 sch_obj = School(name="OldBoyBeijing")
12 db_session.add(sch_obj)
13 db_session.commit()
14 sch = db_session.query(School).filter(School.name =="OldBoyBeijing").first()
15 stu_obj = Student(name="Yuan",school_id=sch.id)
16 db_session.add(stu_obj)
17 db_session.commit()
18 db_session.close()
19 
20 # 添加数据  反向添加 relationship
21 
22 sch_obj = School(name="OldBoyShanghai")
23 sch_obj.sch2stu = [Student(name="江疏影"),Student(name="周冬雨"),]
24 db_session.add(sch_obj)
25 db_session.commit()
26 db_session.close()
27 
28 
29 # 添加数据 正向添加   relationship
30 stu_obj = Student(name="大黄鸭",stu2sch = School(name="OldBoyShenzhen"))
31 db_session.add(stu_obj)
32 db_session.commit()
33 db_session.close()
    添加数据

    查询数据

     1 #   查询数据
 2 
 3 
 4 from sqlalchemy.orm import sessionmaker
 5 from creat_table_ForeignKey import engine,Student,School
 6 
 7 Session = sessionmaker(engine)
 8 db_session = Session()
 9 
10 # #1.查询数据  正向查询数据  relationship
11 stu = db_session.query(Student).all()
12 for row in stu:
13     print(row.id,row.name,row.school_id,row.stu2sch.name)
14 
15 
16 # #1.查询数据  反向查询数据  relationship
17 
18 sch = db_session.query(School).all()
19 for school in sch:
20     for student in school.sch2stu:
21         print(school.id,school.name,student.name)
    查询数据

     修改数据

     1 #   更新数据
 2 
 3 
 4 from sqlalchemy.orm import sessionmaker
 5 from creat_table_ForeignKey import engine,Student,School
 6 
 7 Session = sessionmaker(engine)
 8 db_session = Session()
 9 
10 # 修改数据
11 
12 sch = db_session.query(School).filter(School.name=="OldBoyShanghai").first()
13 db_session.query(Student).filter(Student.name == "大黄鸭").update({"school_id":sch.id})
14 db_session.commit()
15 db_session.close()
    修改数据

    删除数据

     1 #   删除数据
 2 
 3 
 4 from sqlalchemy.orm import sessionmaker
 5 from creat_table_ForeignKey import engine,Student,School
 6 
 7 Session = sessionmaker(engine)
 8 db_session = Session()
 9 
10 # 删除数据
11 
12 sch = db_session.query(School).filter(School.name=="OldBoyShanghai").first()
13 db_session.query(Student).filter(Student.school_id == sch.id).delete()
14 db_session.commit()
15 db_session.close()
    删除数据

    高级版的查询操作

      1 # 高级版查询操作,厉害了哦
  2 #老规矩
  3 from my_create_table import User,engine
  4 from sqlalchemy.orm import sessionmaker
  5 
  6 Session = sessionmaker(engine)
  7 db_session = Session()
  8 
  9 # 查询数据表操作
 10 # and or
 11 from sqlalchemy.sql import and_ , or_
 12 ret = db_session.query(User).filter(and_(User.id > 3, User.name == 'DragonFire')).all()
 13 ret = db_session.query(User).filter(or_(User.id < 2, User.name == 'DragonFire')).all()
 14 
 15 # 查询所有数据
 16 r1 = db_session.query(User).all()
 17 
 18 # 查询数据 指定查询数据列 加入别名
 19 r2 = db_session.query(User.name.label('username'), User.id).first()
 20 print(r2.id,r2.username) # 15 NBDragon
 21 
 22 # 表达式筛选条件
 23 r3 = db_session.query(User).filter(User.name == "DragonFire").all()
 24 
 25 # 原生SQL筛选条件
 26 r4 = db_session.query(User).filter_by(name='DragonFire').all()
 27 r5 = db_session.query(User).filter_by(name='DragonFire').first()
 28 
 29 # 字符串匹配方式筛选条件 并使用 order_by进行排序
 30 r6 = db_session.query(User).filter(text("id<:value and name=:name")).params(value=224, name='DragonFire').order_by(User.id).all()
 31 
 32 #原生SQL查询
 33 r7 = db_session.query(User).from_statement(text("SELECT * FROM User where name=:name")).params(name='DragonFire').all()
 34 
 35 # 筛选查询列
 36 # query的时候我们不在使用User ORM对象,而是使用User.name来对内容进行选取
 37 user_list = db_session.query(User.name).all()
 38 print(user_list)
 39 for row in user_list:
 40     print(row.name)
 41 
 42 # 别名映射  name as nick
 43 user_list = db_session.query(User.name.label("nick")).all()
 44 print(user_list)
 45 for row in user_list:
 46     print(row.nick) # 这里要写别名了
 47 
 48 # 筛选条件格式
 49 user_list = db_session.query(User).filter(User.name == "DragonFire").all()
 50 user_list = db_session.query(User).filter(User.name == "DragonFire").first()
 51 user_list = db_session.query(User).filter_by(name="DragonFire").first()
 52 for row in user_list:
 53     print(row.nick)
 54 
 55 # 复杂查询
 56 from sqlalchemy.sql import text
 57 user_list = db_session.query(User).filter(text("id<:value and name=:name")).params(value=3,name="DragonFire")
 58 
 59 # 查询语句
 60 from sqlalchemy.sql import text
 61 user_list = db_session.query(User).filter(text("select * from User id<:value and name=:name")).params(value=3,name="DragonFire")
 62 
 63 # 排序 :
 64 user_list = db_session.query(User).order_by(User.id).all()
 65 user_list = db_session.query(User).order_by(User.id.desc()).all()
 66 for row in user_list:
 67     print(row.name,row.id)
 68 
 69 #其他查询条件
 70 """
 71 ret = session.query(User).filter_by(name='DragonFire').all()
 72 ret = session.query(User).filter(User.id > 1, User.name == 'DragonFire').all()
 73 ret = session.query(User).filter(User.id.between(1, 3), User.name == 'DragonFire').all() # between 大于1小于3的
 74 ret = session.query(User).filter(User.id.in_([1,3,4])).all() # in_([1,3,4]) 只查询id等于1,3,4的
 75 ret = session.query(User).filter(~User.id.in_([1,3,4])).all() # ~xxxx.in_([1,3,4]) 查询不等于1,3,4的
 76 ret = session.query(User).filter(User.id.in_(session.query(User.id).filter_by(name='DragonFire'))).all() 子查询
 77 from sqlalchemy import and_, or_
 78 ret = session.query(User).filter(and_(User.id > 3, User.name == 'DragonFire')).all()
 79 ret = session.query(User).filter(or_(User.id < 2, User.name == 'DragonFire')).all()
 80 ret = session.query(User).filter(
 81     or_(
 82         User.id < 2,
 83         and_(User.name == 'eric', User.id > 3),
 84         User.extra != ""
 85     )).all()
 86 # select * from User where id<2 or (name="eric" and id>3) or extra != "" 
 87 
 88 # 通配符
 89 ret = db_session.query(User).filter(User.name.like('e%')).all()
 90 ret = db_session.query(User).filter(~User.name.like('e%')).all()
 91 
 92 # 限制
 93 ret = db_session.query(User)[1:2]
 94 
 95 # 排序
 96 ret = db_session.query(User).order_by(User.name.desc()).all()
 97 ret = db_session.query(User).order_by(User.name.desc(), User.id.asc()).all()
 98 
 99 # 分组
100 from sqlalchemy.sql import func
101 
102 ret = db_session.query(User).group_by(User.extra).all()
103 ret = db_session.query(
104     func.max(User.id),
105     func.sum(User.id),
106     func.min(User.id)).group_by(User.name).all()
107 
108 ret = db_session.query(
109     func.max(User.id),
110     func.sum(User.id),
111     func.min(User.id)).group_by(User.name).having(func.min(User.id) >2).all()
112 """
113 
114 # 关闭连接
115 db_session.close()
116 
117 orm_select_more
    高级版查询操作

     高级修改数据操作

     1 #高级版更新操作
 2 from my_create_table import User,engine
 3 from sqlalchemy.orm import sessionmaker
 4 
 5 Session = sessionmaker(engine)
 6 db_session = Session()
 7 
 8 #直接修改
 9 db_session.query(User).filter(User.id > 0).update({"name" : "099"})
10 
11 #在原有值基础上添加 - 1
12 db_session.query(User).filter(User.id > 0).update({User.name: User.name + "099"}, synchronize_session=False)
13 
14 #在原有值基础上添加 - 2
15 db_session.query(User).filter(User.id > 0).update({"age": User.age + 1}, synchronize_session="evaluate")
16 db_session.commit()
17 
18 orm_update_more
    高级修改操作

    建立多对多：的ManyToMany

    创建表关系：

     1 from sqlalchemy.ext.declarative import declarative_base
 2 
 3 Base = declarative_base()
 4 
 5 from sqlalchemy import Column,Integer,String,ForeignKey
 6 from sqlalchemy.orm import relationship
 7 
 8 class Hotel(Base):
 9     __tablename__="hotel"
10     id=Column(Integer,primary_key=True)
11     girl_id = Column(Integer,ForeignKey("girl.id"))
12     boy_id = Column(Integer,ForeignKey("boy.id"))
13 
14 class Girl(Base):
15     __tablename__="girl"
16     id=Column(Integer,primary_key=True)
17     name = Column(String(32),index=True)
18 
19     #创建关系
20     boys = relationship("Boy",secondary="hotel",backref="girl2boy")
21 
22 
23 class Boy(Base):
24     __tablename__="boy"
25     id=Column(Integer,primary_key=True)
26     name = Column(String(32),index=True)
27 
28 
29 from sqlalchemy import create_engine
30 engine = create_engine("mysql+pymysql://root:DragonFire@127.0.0.1:3306/dragon?charset=utf8")
31 
32 Base.metadata.create_all(engine)
33 
34 my_M2M.py
35 
36 my_M2M.py
    创建表关系

    基于relationship增加数据：

     1 from my_M2M import Girl,Boy,Hotel,engine
 2 
 3 # 创建连接
 4 from sqlalchemy.orm import sessionmaker
 5 # 创建数据表操作对象 sessionmaker
 6 DB_session = sessionmaker(engine)
 7 db_session = DB_session()
 8 
 9 # 1.通过Boy添加Girl和Hotel数据
10 boy = Boy(name="DragonFire")
11 boy.girl2boy = [Girl(name="赵丽颖"),Girl(name="Angelababy")]
12 db_session.add(boy)
13 db_session.commit()
14 
15 # 2.通过Girl添加Boy和Hotel数据
16 girl = Girl(name="珊珊")
17 girl.boys = [Boy(name="Dragon")]
18 db_session.add(girl)
19 db_session.commit()
20 
21 orm_M2M_insert.py
22 
23 orm_M2M_insert.py
    基于relationship增加数据

    基于relationship查询数据：

     1 from my_M2M import Girl,Boy,Hotel,engine
 2 
 3 # 创建连接
 4 from sqlalchemy.orm import sessionmaker
 5 # 创建数据表操作对象 sessionmaker
 6 DB_session = sessionmaker(engine)
 7 db_session = DB_session()
 8 
 9 # 1.通过Boy查询约会过的所有Girl
10 hotel = db_session.query(Boy).all()
11 for row in hotel:
12     for row2 in row.girl2boy:
13         print(row.name,row2.name)
14 
15 # 2.通过Girl查询约会过的所有Boy
16 hotel = db_session.query(Girl).all()
17 for row in hotel:
18     for row2 in row.boys:
19         print(row.name,row2.name)
20 
21 orm_M2M_select.py
22 
23 orm_M2M_select.py
    基于relationship查询数据
  • 相关阅读:
    ASP.NET缓存全解析（系列）
    updateprogress用法技巧
    text与img对齐
    9款Firefox插件提高设计开发效率
    ASP.NET页面实时进行GZIP压缩优化
    如何收缩和删除SQL日志文件
    闲扯加班
    与大家分享一点游戏管理晋升的心得（完整版）
    FDS (Flex Data Services)
    和我老婆去旅游
  • 原文地址：https://www.cnblogs.com/wqzn/p/10385673.html
Copyright © 2011-2022 走看看