SQLAlcvchem

一.安装(稳定版的1.2.17)

二.一般使用(切记切记不要使用模块的名字作为项目名字,否则会出现玄学解决不了的问题------坑)

#1.导入SQLALchemy from sqlalchemy.ext.declarative import declarative_base #2.创建ORM模型基类 Base = declarative_base() #3.导入ORM对应数据类型的字段 from sqlalchemy import Column,Integer,String #4.创建ORM对象 class User(Base): __tablename__ ="user" #创建表名字 id = Column(Integer,primary_key=True,autoincrement=True) #创建id主键自增长 name = Column(String(32),index=True) #5创建数据库链接 from sqlalchemy import create_engine engine = create_engine("mysql+pymysql://root:@127.0.0.1:3306/day127?charset=utf8") #6去数据库中创建与User所对应的数据库 Base.metadata.create_all(engine)

 三.创建外键关联

from sqlalchemy.ext.declarative import declarative_base Base = declarative_base() from sqlalchemy import Column,String,ForeignKey,Integer from sqlalchemy.orm import relationship class Student(Base): __tablename__ ="student" id = Column(Integer,primary_key=True) name = Column(String(32)) school_id = Column(Integer,ForeignKey("school.id")) stu2sch = relationship("School",backref="sch2stu") class School(Base): __tablename__="school" id = Column(Integer,primary_key=True) name = Column(String(32)) from sqlalchemy import create_engine engine = create_engine("mysql+pymysql://root:@127.0.0.1:3306/127?charset=utf8") Base.metadata.create_all(engine)

四.增加数据

# 通过SQLAlchemy对数据表进行增删改查 # crud == 增删改查 # 想要操纵数据库 打开数据库连接 # from sqlalchemy import create_engine # engine = create_engine("mysql+pymysql://root:@127.0.0.1:3306/day127?charset=utf8") from create_table import engine # 创建会话 - 打开数据库连接 from sqlalchemy.orm import sessionmaker # 创建会话窗口 Session = sessionmaker(engine) # 打开会话窗口 db_session = Session() # 1.增加数据 == insert # # insert into user(name) values("DragonFire") # from create_table import User # user_obj = User(name="Ywb") # # 通过db_session已经打开会话窗口 提交数据 # db_session.add(user_obj) # insert into # # 执行会话窗口中的所有操作 # db_session.commit() #rud # db_session.close() # 2.增加批量数据 # from create_table import User # db_session.add_all([ # User(name="AlexDSB"), # User(name="DragonFire"), # User(name="赵丽颖") # ]) # # db_session.commit() # db_session.close() #扩展： # from create_table import User # user1 = User(name="666") # user2 = User(name="777") # user3 = User(name="888") # # db_session.add(user1) # db_session.add(user2) # db_session.add(user3) # # db_session.commit() # db_session.close()

4.1外键增加数据

# 添加数据 from sqlalchemy.orm import sessionmaker from create_table_ForeignKey import engine,Student,School Session = sessionmaker(engine) db_session = Session() # 1.添加数据 - 笨 # sch_obj = School(name="OldBoyBeijing") # db_session.add(sch_obj) # db_session.commit() # # sch = db_session.query(School).filter(School.name == "OldBoyBeijing").first() # stu_obj = Student(name="DragonFire",school_id=sch.id) # db_session.add(stu_obj) # db_session.commit() # db_session.close() # 2.添加数据 - 正向 relationship 版 # stu_obj = Student(name="小笼包",stu2sch=School(name="OldBoyShenzhen")) # db_session.add(stu_obj) # db_session.commit() # db_session.close() # 3.添加数据 - 反向 relationship 版 # sch_obj = School(name="OldBoyShanghai") # sch_obj.sch2stu = [Student(name="赵丽颖"),Student(name="陈妍希")] # db_session.add(sch_obj) # db_session.commit() # db_session.close()

五.删除数据

# 添加数据 from sqlalchemy.orm import sessionmaker from create_table_ForeignKey import engine,Student,School Session = sessionmaker(engine) db_session = Session() # 1.添加数据 - 笨 # sch_obj = School(name="OldBoyBeijing") # db_session.add(sch_obj) # db_session.commit() # # sch = db_session.query(School).filter(School.name == "OldBoyBeijing").first() # stu_obj = Student(name="DragonFire",school_id=sch.id) # db_session.add(stu_obj) # db_session.commit() # db_session.close() # 2.添加数据 - 正向 relationship 版 # stu_obj = Student(name="小笼包",stu2sch=School(name="OldBoyShenzhen")) # db_session.add(stu_obj) # db_session.commit() # db_session.close() # 3.添加数据 - 反向 relationship 版 # sch_obj = School(name="OldBoyShanghai") # sch_obj.sch2stu = [Student(name="赵丽颖"),Student(name="陈妍希")] # db_session.add(sch_obj) # db_session.commit() # db_session.close()

5.1外键删除数据

# 添加数据 from sqlalchemy.orm import sessionmaker from create_table_ForeignKey import engine,Student,School Session = sessionmaker(engine) db_session = Session() # 删除数据 sch = db_session.query(School).filter(School.name=="OldBoyShanghai").first() db_session.query(Student).filter(Student.school_id == sch.id).delete() db_session.commit() db_session.close()

六.查询数据

# 查询 # 会话窗口 from sqlalchemy.orm import sessionmaker from create_table import engine Session = sessionmaker(engine) db_session = Session() from create_table import User # 1.简单查询 # select * from table # user_list = db_session.query(User).all() # for row in user_list: # print(row.id,row.name) # user = db_session.query(User).first() # print(user.id,user.name) # 2.带条件的查询 # user_list = db_session.query(User).filter(User.id == 4).all() # print(user_list[0].id,user_list[0].name) # user = db_session.query(User).filter_by(id=4).first() # print(user.id,user.name) # user_list = db_session.query(User).filter(User.id >= 4).all() # for row in user_list: # print(row.name,row.id) # 扩展 查看sql语句 # sql = db_session.query(User).filter(User.id >= 4) # print(sql)

6.1外键查询

# 添加数据 from sqlalchemy.orm import sessionmaker from create_table_ForeignKey import engine,Student,School Session = sessionmaker(engine) db_session = Session() # 1.查询数据 - relationship 版 正向 # stu = db_session.query(Student).all() # for row in stu: # print(row.id,row.name,row.school_id,row.stu2sch.name) # 2.查询数据 - relationship 版 反向 # sch = db_session.query(School).all() # for school in sch: # for student in school.sch2stu: # print(school.id,school.name,student.name)

6.2补充--查询

# 高级版查询操作,厉害了哦 # 老规矩 from create_table import User, engine from sqlalchemy.orm import sessionmaker Session = sessionmaker(engine) db_session = Session() # 查询数据表操作 # and or # res = db_session.query(User).filter(User.id == 4 or User.name == "DragonFire").all() # print(res[0].name,res) # # if False and True: # print("lihaile") # from sqlalchemy.sql import and_ , or_ # ret = db_session.query(User).filter(and_(User.id == 3, User.name == 'DragonFire')).all() # print(ret) # ret = db_session.query(User).filter(or_(User.id == 4, User.name == 'DragonFire')).all() # print(ret) # ret = db_session.query(User).filter_by(id=4,name="DragonFire").all() # print(ret) # 查询所有数据 # r1 = db_session.query(User).all() # 查询数据 指定查询数据列 加入别名 # r2 = db_session.query(User.id.label("uid"),User.name.label("username")).first() # print(r2.uid,r2.username) # 15 NBDragon # 表达式筛选条件 # r3 = db_session.query(User).filter(User.name == "DragonFire").all() # 原生SQL筛选条件 # r4 = db_session.query(User).filter_by(name='DragonFire').all() # r5 = db_session.query(User).filter_by(name='DragonFire').first() # 字符串匹配方式筛选条件 并使用 order_by进行排序 # from sqlalchemy.sql import text # r6 = db_session.query(User).filter(text("id=:value and name=:name")).params(value=3, name='DragonFire').first() # print(r6.name) # 原生SQL查询 # r7 = db_session.query(User).from_statement(text("SELECT * FROM User where name=:name")).params(name='DragonFire').all() # 筛选查询列 # 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 # user_list = db_session.query(User.name).all() # print(user_list) # for row in user_list: # print(row.name) # 别名映射 name as nick # user_list = db_session.query(User.name.label("nick")).all() # print(user_list) # for row in user_list: # print(row.nick) # 这里要写别名了 # 筛选条件格式 # user_list = db_session.query(User).filter(User.name == "DragonFire").all() # user_list = db_session.query(User).filter(User.name == "DragonFire").first() # user_list = db_session.query(User).filter_by(name="DragonFire").first() # for row in user_list: # print(row.nick) # 复杂查询 # from sqlalchemy.sql import text # user_list = db_session.query(User).filter(text("id<:value and name=:name")).params(value=3,name="DragonFire") # 查询语句 # from sqlalchemy.sql import text # user_list = db_session.query(User).filter(text("select * from User id<:value and name=:name")).params(value=3,name="DragonFire") # 排序 : # user_list = db_session.query(User).order_by(User.id.asc()).all() # user_list = db_session.query(User).order_by(User.id.desc()).all() # for row in user_list: # print(row.name,row.id) # 其他查询条件 """ ret = session.query(User).filter_by(name='DragonFire').all() ret = session.query(User).filter(User.id > 1, User.name == 'DragonFire').all() ret = session.query(User).filter(User.id.between(1, 3), User.name == 'DragonFire').all() # between 大于1小于3的 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 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 ret = session.query(User).filter(User.id.in_(session.query(User.id).filter_by(name='DragonFire'))).all() 子查询 from sqlalchemy import and_, or_ ret = session.query(User).filter(and_(User.id > 3, User.name == 'DragonFire')).all() ret = session.query(User).filter(or_(User.id < 2, User.name == 'DragonFire')).all() ret = session.query(User).filter( or_( User.id < 2, and_(User.name == 'eric', User.id > 3), User.extra != "" )).all() # select * from User where id<2 or (name="eric" and id>3) or extra != "" # 通配符 ret = db_session.query(User).filter(User.name.like('e%')).all() ret = db_session.query(User).filter(~User.name.like('e%')).all() # 限制 ret = db_session.query(User)[1:2] # 排序 ret = db_session.query(User).order_by(User.name.desc()).all() ret = db_session.query(User).order_by(User.name.desc(), User.id.asc()).all() # 分组 from sqlalchemy.sql import func ret = db_session.query(User).group_by(User.extra).all() ret = db_session.query( func.max(User.id), func.sum(User.id), func.min(User.id)).group_by(User.name).all() ret = db_session.query( func.max(User.id), func.sum(User.id), func.min(User.id)).group_by(User.name).having(func.min(User.id) >2).all() """ # ret = db_session.query(User).filter(User.id.between(1, 3)).all() # between 大于1小于3的 # print(ret) # ret = db_session.query(User).filter(User.id.in_([1,4])).all() # in_([1,3,4]) 只查询id等于1,3,4的 # ret = db_session.query(User).filter(~User.id.in_([1,2,3])).all() # ~xxxx.in_([1,3,4]) 查询不等于1,3,4的 # print(ret) # from sqlalchemy.sql import and_, or_ # # ret = db_session.query(User).filter( # or_( # User.id < 2, # and_(User.name == 'eric', User.id > 3), # User.name != "" # )) # print(ret) # 关闭连接 db_session.close()

七更新数据

# 更新修改数据 from sqlalchemy.orm import sessionmaker from create_table import engine, User Session = sessionmaker(engine) db_session = Session() # 1.修改数据 - 先查询预修改的数据 # update `user` set `name` = "666" where id = 1 # res = db_session.query(User).filter(User.name=="Ywb").update({"name":"武配齐"}) # print(res) # db_session.commit() # db_session.close() # res = db_session.query(User).filter(User.id >= 5).update({"name":123456}) # print(res) # db_session.commit() # db_session.close()

7.1外键更新数据

# 添加数据 from sqlalchemy.orm import sessionmaker from create_table_ForeignKey import engine,Student,School Session = sessionmaker(engine) db_session = Session() # 修改数据 sch = db_session.query(School).filter(School.name=="OldBoyShanghai").first() db_session.query(Student).filter(Student.name == "小笼包").update({"school_id":sch.id}) db_session.commit() db_session.close()

7.2补充更新

#高级版更新操作 from create_table import User,engine from sqlalchemy.orm import sessionmaker Session = sessionmaker(engine) db_session = Session() #直接修改 # db_session.query(User).filter(User.id > 0).update({"name" : "099"}) #在原有值基础上添加 - 1 db_session.query(User).filter(User.id > 0).update({User.name: User.name + "099"}, synchronize_session=False) db_session.commit() #在原有值基础上添加 - 2 # db_session.query(User).filter(User.id > 0).update({"age": User.age + 1}, synchronize_session="evaluate") # db_session.commit()

 八.多对多的表结构建立

from sqlalchemy.ext.declarative import declarative_base Base = declarative_base() from sqlalchemy import Column,Integer,String,ForeignKey from sqlalchemy.orm import relationship class Girls(Base): __tablename__ = "girl" id = Column(Integer(),primary_key=True,autoincrement=True) name = Column(String(32)) girl2boy = relationship("Boy",secondary="Hote",backref="boy2girl") class Boy(Base): __tablename__ ="boy" id = Column(Integer(),primary_key=True,autoincrement=True) name = Column(String(32)) class Hote(Base): __tablename__ ="hote" id = Column(Integer(),primary_key=True,autoincrement=True) name = Column(String(32)) girl_id = Column(Integer, ForeignKey("girl.id")) boy_id = Column(Integer, ForeignKey("boy.id")) from sqlalchemy import create_engine engine = create_engine("mysql+pymysql://root:@127.0.0.1:3306/day127?charset=utf8") Base.metadata.create_all(engine)

8.1多对多的增加数据

from sqlalchemy.orm import sessionmaker from app.M2m import engine Session = sessionmaker(engine) db_session = Session() #1.增加 # 1.通过Boy添加Girl和Hotel数据 boy = Boy(name="DragonFire") boy.girl2boy = [Girls(name="赵丽颖"),Girls(name="Angelababy")] db_session.add(boy) db_session.commit() # 2.通过Girl添加Boy和Hotel数据 girl = Girls(name="珊珊") girl.boys = [Boy(name="Dragon")] db_session.add(girl) db_session.commit()

8.2多对多的查询数据

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)

 

转载于:https://www.cnblogs.com/RootEvils/p/10374147.html

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