sqlalchemy连接MySQL数据库基本操作

sqlalchemy_test.py

#!/usr/bin/env python3.8.6
# _*_ coding: utf-8 _*_
# Description:
# Author: qiaoxiaohang <qiaoxiaohang@beyondsoft.com>
# Date: 2022/4/8




from config import DB_URI
from sqlalchemy import create_engine


#todo 创建引擎并链接数据库
# engine = create_engine(DB_URI)#创建引擎
# conn = engine.connect()#链接
# result = conn.execute('select * from boo')
# print(result.fetchone())
# conn.close()#关闭链接


# todo 创建ORM模型并映射到数据库中

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

engine = create_engine(DB_URI)#建立引擎
Base = declarative_base(engine)# 建立 sql rom基类
session = sessionmaker(engine)() #构建session对象

#todo 创建数据库表
'''
创建数据库表student
class Student(Base):
    __tablename__ = "student"
    id = Column(Integer,primary_key=True,autoincrement=True)
    name = Column(String(50))
    age = Column(Integer)
    sex = Column(String(10))

Base.metadata.create_all()# 将模型映射到数据库中
'''
#todo 新增数据
class Student(Base):
    __tablename__ = "student"
    id = Column(Integer,primary_key=True,autoincrement=True)
    name = Column(String(50))
    age = Column(Integer)
    sex = Column(String(10))

'''
student = Student(name='Tony',age = 16,sex = 'male')
session.add(student)#单个数据插入
session.commit()
-----------------------------------------------------
session.add_all([
    Student(name='Jane', age=16, sex='female'),
    Student(name='Ben', age=20, sex='male')
])#批量插入数据
session.commit()
'''

#todo 查询数据 --sqlalchemy提供了query()方法来查询数据
data_list = session.query(Student).all()
print(data_list)
for data in data_list:
    print(data.name,data.age,data.sex)
#输出：
# [<__main__.Student object at 0x0000016EE319B310>, <__main__.Student object at 0x0000016EE319B280>, <__main__.Student object at 0x0000016EE319B370>]
# Tony 16 male
# Jane 16 female
# Ben 20 male
#todo 指定查询
name_list = session.query(Student.name).all()
# name_list = session.query(Student.name).first()#获取返回数据的第一行
print(name_list)
# 输出:[('Tony',), ('Jane',), ('Ben',)]
#todo  使用filter()方法进行筛选过滤
filter_list = session.query(Student.name).filter(Student.age>=18).all()
print(filter_list)#输出：[('Tony',), ('Ben',)]

#todo 使用order_by()进行排序

item_list = session.query(Student.name, Student.age).order_by(Student.age.desc()).all() # desc()表示倒序
print(item_list)

# [('Ben', 20), ('Tony', 18), ('Jane', 16)]

# todo 多个查询条件(and和or)
# 默认为and, 在filter()中用,分隔多个条件表示and
item_list = session.query(Student.name, Student.age, Student.sex).filter(
    Student.age >= 10, Student.sex == 'female'
).all()
print(item_list)  # [('Jane', 16, 'female')]


from sqlalchemy import or_

# 使用or_连接多个条件
item_list = session.query(Student.name, Student.age, Student.sex).filter(
    or_(Student.age >= 20, Student.sex == 'female')
).all()
print(item_list)  # [('Jane', 16, 'female'), ('Ben', 20, 'male')]


# todo equal/like/in
# 等于
item_list = session.query(Student.name, Student.age, Student.sex).filter(
    Student.age == 18
).all()
print(item_list)  # [('Tony', 18, 'male')]

# 不等于
item_list = session.query(Student.name, Student.age, Student.sex).filter(
    Student.age != 18
).all()
print(item_list)  # [('Jane', 16, 'female'), ('Ben', 20, 'male')]

# like
item_list = session.query(Student.name, Student.age, Student.sex).filter(
    Student.name.like('%To%')
).all()
print(item_list)  # [('Tony', 18, 'male')]

# in
item_list = session.query(Student.name, Student.age, Student.sex).filter(
    Student.age.in_([16, 20])
).all()
print(item_list) # [('Jane', 16, 'female'), ('Ben', 20, 'male')]


# todo count计算个数
count = session.query(Student).count()
print(count)  # 3


# todo 切片
item_list = session.query(Student.name).all()[:2]
print(item_list)  # [('Tony',), ('Jane',)]

#todo 修改数据
#修改数据可以使用update()方法，update完成后记得执行session.commit()
# 修改Tony的age为22
session.query(Student).filter(Student.name == 'Tony').update({'age': 22})
session.commit()

item = session.query(Student.name, Student.age).filter(Student.name == 'Tony').first()
print(item) #('Tony', 22)

# todo 删除数据
# 删除数据使用delete()方法，同样也需要执行session.commit()提交事务
# 删除名称为Ben的数据
session.query(Student).filter(Student.name == 'Ben').delete()
session.commit()

item_list = session.query(Student.name, Student.age).all()
print(item_list)#[('Tony', 22), ('Jane', 16)]

数据库配置参数

config.py

#!/usr/bin/env python3.8.6
# _*_ coding: utf-8 _*_
# Description:
# Author: qiaoxiaohang <qiaoxiaohang@beyondsoft.com>
# Date: 2022/4/8
HOST = 'localhost'
PORT = 3306
USERNAME = 'root'
PASSWORD = '123456'
DB = 'test'
DB_URI = f'mysql+pymysql://{USERNAME}:{PASSWORD}@{HOST}:{PORT}/{DB}'

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