python 笔记 之 sqlalchemy操作数据库-增删改查

'''
sqlalchemy
操作数据库--增删改查

'''

from sqlalchemy import create_engine, Column, Integer, String
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker

engine = create_engine('mysql+pymysql://chen:[email protected]/sqlalchemy')
DBsession = sessionmaker(bind=engine)
session = DBsession()
Base = declarative_base()

#类对应数据库中的表字段，一个实例就是一行数据
class Student(Base):
    __tablname__ = "student"
    id = Column(Integer,primary_key=True)
    name = Column(String(50))
    age = Column(Integer)
    address = Column(String(50))

#insert 增
st1 = Student(id=1001,name='ling',age=25,address='BeiJing')
st2 = Student(id=1002,name='molin',age=18,address='shanghai')
st3 = Student(id=1003,name='cc',age=23,address='zhuhai')
st4 = Student(id=1004,name='lieeeeng',age=32,address='hangzhou')

session.add_all([st1,st2,st3,st4])
session.commit()

#select查
a = session.query(Student).filter_by(name="ling").first()
print(a)
print(a.id)
print(a.name)
print(a.age)
print(a.address)
'''
filter_by 和 filter
filter_by(name="ling") 不能使用 > < =
filter(Student.id>1001) 必须使用 Student.id 可以使用 > < =
'''
a = session.query(Student).filter(Student.id>1001).all()
for i in a:
    print(i.id)
    print(i.name)
    print(i.age)
    print(i.sex)
    print(i.address)