python 笔记 之 复习-数据库操作-封装的操作

'''
复习
数据库操作-封装的操作
'''

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

Base = declarative_base()
class Student(Base):
    __tablname__ = "student"
    id = Column(Integer,primary_key=True)
    name = Column(String(50))
    age = Column(Integer)
    address = Column(String(50))
# 增
def insert(session):
    st = Student(id=1005, name='nnn', age=16,
                  address='zhangjiang')
    session.add(st)
    session.commit()
#改
def update(session):
    st1 = session.query(Student).filter(Student.id == 1001).one()
    st1.name = "test"
    session.commit()
#查
def select(session):
    stu2 = session.query(Student).filter(Student.id == 1001).one()
    print(stu2)
#删
def delete(session):
    st1 = session.query(Student).filter(Student.id == 1001).delete()
    session.commit()
#统计
def count(session):
    number = session.query(Student).filter().count()
    print("total Student is {0}".format(number))
#分组
def groupBy(session):
    groupByName = session.query(Student).group_by(Student.name).one()
    groupByAge = session.query(Student).group_by(Student.age).one()
    print(groupByName)
    print(groupByAge)
    for i in groupByAge:
        print(i.id,i.name,i.age,i.address)
#排序
def orderBy(session):
    orderBy = session.query(Student).order_by(Student.age).all()
    orderByDesc = session.query(Student).order_by(Student.age.desc()).all() #反序
    print(orderBy)
    for i in orderByDesc:
        print(i.id,i.name,i.age,i.address)
#初始化，链接数据库，调用函数
def main():
    engine = create_engine('mysql+pymysql://chen:[email protected]/sqlalchemy')
    DBsession = sessionmaker(bind=engine)
    session = DBsession()
    select(session)
    update(session)
    select(session)
    delete(session)
    count(session)
    groupBy(session)
    orderBy(session)

if __name__ == '__main__':
    main()