Python9-MySQL-MySQL-ORM框架-day48

ORM框架：AQLAlchemy
-作用：
    1、提供简单的规则
    2、自动转换成SQL语句

-DB first: 手动创建数据库以及表 -> ORM框架 -> 自动生成类
 code first：手动创建类        ->ORM框架  -> 以及表
功能：
    -创建数据库表
        连接数据库（非SQLAlchemy,是pymsql）
        类转换SQL语句
    -操作数据行
        增
        删
        改
        查

from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index
from sqlalchemy.orm import sessionmaker, relationship
from sqlalchemy import create_engine

Base = declarative_base()
# 创建单表
class UserType(Base):
    __tablename__ = 'usertype'
    id = Column(Integer, primary_key=True,autoincrement=True)
    name = Column(String(32),nullable=True,default='sf',index=True)

class Users(Base):
    __tablename__ = 'users'
    id = Column(Integer, primary_key=True,autoincrement=True)
    name = Column(String(32),nullable=True,default='sf',index=True)
    extra = Column(String(16),unique=True)
    user_type_id = Column(Integer,ForeignKey('usertype.id'))
def create_db():
    engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/t1", max_overflow=5)
    Base.metadata.create_all(engine)
def delete_db():
    engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/t1", max_overflow=5)
    Base.metadata.drop_all(engine)

#增加
obj1 = UserType(name='普通用户')
session.add(obj1)
session.commit()

# obj1 = UserType(name='普通用户')
objs=[
     UserType(name='超级用户'),
     UserType(name='白金用户'),
     UserType(name='黑金用户')
]
# session.add(obj1)
session.add_all(objs)
session.commit()
session.close()

#修改
# session.query(UserType.id,UserType.name).filter(UserType.id>0).update({'name':'黑金'})
session.query(UserType.id,UserType.name).filter(UserType.id>2).update({UserType.name: UserType.name + "xxx"}, synchronize_session=False)
session.commit()
session.close()

　　

# 删
# session.query(UserType.id,UserType.name).filter(UserType.id>3).delete()

# 查
# user_type_list = session.query(UserType).all()
# for row in user_type_list:
#     print(row.id,row.name)
# user_type_list = session.query(UserType.id,UserType.name).filter(UserType.id>2)
# for row in user_type_list:
#     print(row.id,row.name)