python orm 框架中sqlalchemy用法实例详解

本文实例讲述了python orm 框架中sqlalchemy用法。分享给大家供大家参考，具体如下：

一.ORM简介

1. ORM(Object-Relational Mapping,对象关系映射):作用是在关系型数据库和业务实体对象之间做一个映射.

2. ORM优点:

向开发者屏蔽了数据库的细节,使开发者无需与SQL语句打交道,提高了开发效率;

便于数据库的迁移,由于每种数据库的SQL语法有差别,基于Sql的数据访问层在更换数据库时通过需要花费时间调试SQL时间,而ORM提供了独立于SQL的接口,ORM的引擎会处理不同数据库之间的差异,所以迁移数据库时无需更改代码.

应用缓存优化等技术有时可以提高数据库操作的效率.

3. SQLALchemy:是python中最成熟的ORM框架,资源和文档很丰富,大多数python web框架对其有很好的主持,能够胜任大多数应用场合,SQLALchemy被认为是python事实上的ORM标准.

二、代码

1.建表

"""
Created on 19-10-22
@author: apple
@description:建表
"""
import pymysql
server = '127.0.0.1'
user = 'root'
# dev
password = '123456'
conn = pymysql.connect(server, user, password, database='DataSave') # 获取连接
cursor = conn.cursor() # 获取游标
# "**ENGINE=InnoDB DEFAULT CHARSET=utf8**"-创建表的过程中增加这条，中文就不是乱码
# 创建表
cursor.execute ("""
CREATE TABLE if not exists lamp_result(
  result_id INT NOT NULL auto_increment primary key,
  product_number VARCHAR(100),
  record_time VARCHAR(100),
  lamp_color INT NOT NULL,
  detect_result VARCHAR(100),
  old_pic_path VARCHAR(100),
  result_pic_path VARCHAR(100)
  )
  ENGINE=InnoDB DEFAULT CHARSET=utf8mb4
""")
# 查询数据
cursor.execute('SELECT * FROM lamp_result')
row = cursor.fetchone()
print(row)
# cursor.execute("INSERT INTO user VALUES('%d', '%s','%s','%s','%s')" % ('xiaoming','qwe','ming','@163.com'))
# 提交数据，才会写入表格
conn.commit()
# 关闭游标关闭数据库
cursor.close()
conn.close()

2. 数据存储

"""
Created on 19-10-22
@author: apple
@requirement:Anaconda 4.3.0 (64-bit) Python3.6
@description:数据存储
"""
from sqlalchemy.exc import SQLAlchemyError
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, String, Integer, create_engine
from sqlalchemy.orm import sessionmaker
Base = declarative_base()
# 连接数据库
# alter table students convert to character set utf8;
conn = "mysql+pymysql://root:password@0.0.0.0:3306/DataSave"
engine = create_engine(conn, encoding='UTF8', echo=False) # echo=True 打印日志
# 创建session对象
Session = sessionmaker(bind=engine)
session = Session()
# 数据库表模型ORM
class DataSaveSystem(Base):
  """
  员工自助信息采集系统
  """
  __tablename__ = 'lamp_result' # 定义表名
  # 定义列名
  result_id = Column(Integer, primary_key=True, autoincrement=True, nullable=False)
  product_number = Column(String(50), nullable=True)
  record_time = Column(String(50), nullable=False)
  lamp_color = Column(Integer, nullable=False)
  detect_result = Column(String(100), nullable=False)
  old_pic_path = Column(String(100), nullable=False)
  result_pic_path = Column(String(100), nullable=False)
  def __repr__(self):
    """
    引用该类别，输出结果
    :return:
    """
    return str(self.__dict__)
    # return '<detect_result:{}>'.format(self.detect_result)
# 插入数据
def insert_to_db(product_number=None, record_time=None, lamp_color=None,
         detect_result=None, old_pic_path=None, result_pic_path=None):
  '''
  :param product_number: 产品编号
  :param record_time: 取原图时间
  :param lamp_color: 灯的颜色:1 2 3 4
  :param detect_result: 检测结果
  :param old_pic_path: 原图路径
  :param result_pic_path: 结果图路径
  :return: 数据是否写入成功
  '''
  information_system_instance = DataSaveSystem(
    product_number=product_number,
    record_time=record_time,
    lamp_color=lamp_color,
    detect_result=detect_result,
    old_pic_path=old_pic_path,
    result_pic_path=result_pic_path)
  # session.add_all([
  #   lamp_result(id=2, name="张2", age=19),
  #   lamp_result(id=3, name="张3", age=20)
  # ])
  session.add(information_system_instance)
  try:
    session.commit() # 尝试提交数据库事务
    # print('数据库数据提交成功')
    return {
      "code": 200,
      "status": True,
      "message": "写入数据库成功",
    }
  except SQLAlchemyError as e:
    session.rollback()
    print(e)
    return {
      "code": 500,
      "status": False,
      "message": str(e)
    }
# url = "mysql+pymysql://root:password@0.0.0.1:3306/DataSave"
# # echo为True时，打印sql,可用于调试
# engine = create_engine(url, echo=False, encoding='utf-8', pool_size=5)
# sessionClass = sessionmaker(bind=engine)
# # 创建会话
# session = sessionClass()
# # 查所有,并排序
# stuList = session.query(DataSaveSystem).order_by(DataSaveSystem.result_id).all()
# print(stuList)
#
stu = DataSaveSystem(product_number='id1',
    record_time='20191022170400',
    lamp_color='1',
    detect_result='ok',
    old_pic_path='picture/',
    result_pic_path='d')
# session.add(stu)
stuList = [DataSaveSystem(product_number='id1',
    record_time='20191022170400',
    lamp_color='1',
    detect_result='ok',
    old_pic_path='picture/',
    result_pic_path='d'),
      DataSaveSystem(product_number='id1',
    record_time='20191022170400',
    lamp_color='1',
    detect_result='ok',
    old_pic_path='picture/',
    result_pic_path='d')]
# session.add_all(stuList)
# session.commit()
# print('数据成功')
if __name__ == '__main__':
  result = insert_to_db(stu)
  print(result)

3.数据函数调用

"""
Created on 19-10-31
@author: apple
@requirement:Anaconda 4.3.0 (64-bit) Python3.6
@description:调取函数基类
"""
from data_sql.airconditioning_lamp_datasave.datasave import DataSaveSystem
from sqlalchemy.exc import SQLAlchemyError
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, String, Integer, create_engine
from sqlalchemy.orm import sessionmaker
Base = declarative_base()
# 连接数据库
# alter table students convert to character set utf8;
conn = "mysql+pymysql://root:password@0.0.0.1:3306/DataSave"
engine = create_engine(conn, encoding='UTF8', echo=False) # echo=True 打印日志
# 创建session对象
Session = sessionmaker(bind=engine)
session = Session()
stuList = [DataSaveSystem(product_number='id1',
    record_time='20191022170400',
    lamp_color='1',
    detect_result='ok',
    old_pic_path='picture/',
    result_pic_path='F'),
      DataSaveSystem(product_number='id1',
    record_time='20191022170400',
    lamp_color='1',
    detect_result='ok',
    old_pic_path='picture/',
    result_pic_path='F'),DataSaveSystem(product_number='id1',
    record_time='20191022170400',
    lamp_color='1',
    detect_result='ok',
    old_pic_path='picture/',
    result_pic_path='F'),DataSaveSystem(product_number='id1',
    record_time='20191022170400',
    lamp_color='1',
    detect_result='ok',
    old_pic_path='picture/',
    result_pic_path='F')]
session.add_all(stuList)
session.commit()
print('数据成功')
# # 根据主建查询数据
# result = session.query(DataSaveSystem).get(3)
# print(result.old_pic_path)
# # 查询第一条
# result = session.query(DataSaveSystem).first()
# print(result) #打印对象属性
# 查询表关键字的数据
result = session.query(DataSaveSystem).filter_by(result_pic_path='a/').first()
print(result)
#修改
session.query(DataSaveSystem).filter(DataSaveSystem.result_pic_path=='a/').update({"detect_result":"不合格"})
session.commit()

希望本文所述对大家Python程序设计有所帮助。