本文實例講述了python orm 框架中sqlalchemy用法。分享給大家供大家參考，具體如下：

一.ORM簡介

1. ORM(Object-Relational Mapping,對象關(guān)系映射):作用是在關(guān)系型數(shù)據(jù)庫和業(yè)務(wù)實體對象之間做一個映射.

2. ORM優(yōu)點:

向開發(fā)者屏蔽了數(shù)據(jù)庫的細節(jié),使開發(fā)者無需與SQL語句打交道,提高了開發(fā)效率;

便于數(shù)據(jù)庫的遷移,由于每種數(shù)據(jù)庫的SQL語法有差別,基于Sql的數(shù)據(jù)訪問層在更換數(shù)據(jù)庫時通過需要花費時間調(diào)試SQL時間,而ORM提供了獨立于SQL的接口,ORM的引擎會處理不同數(shù)據(jù)庫之間的差異,所以遷移數(shù)據(jù)庫時無需更改代碼.

應(yīng)用緩存優(yōu)化等技術(shù)有時可以提高數(shù)據(jù)庫操作的效率.

3. SQLALchemy:是python中最成熟的ORM框架,資源和文檔很豐富,大多數(shù)python web框架對其有很好的主持,能夠勝任大多數(shù)應(yīng)用場合,SQLALchemy被認為是python事實上的ORM標準.

二、代碼

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') # 獲取連接

cursor = conn.cursor() # 獲取游標

# "**ENGINE=InnoDB DEFAULT CHARSET=utf8**"-創(chuàng)建表的過程中增加這條，中文就不是亂碼

# 創(chuàng)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

""")

# 查詢數(shù)據(jù)

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'))

# 提交數(shù)據(jù)，才會寫入表格

conn.commit()

# 關(guān)閉游標關(guān)閉數(shù)據(jù)庫

cursor.close()

conn.close()

2. 數(shù)據(jù)存儲

"""

Created on 19-10-22

@author: apple

@requirement:Anaconda 4.3.0 (64-bit) Python3.6

@description:數(shù)據(jù)存儲

"""

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()

# 連接數(shù)據(jù)庫

# 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

# 創(chuàng)建session對象

Session = sessionmaker(bind=engine)

session = Session()

# 數(shù)據(jù)庫表模型ORM

class DataSaveSystem(Base):

"""

員工自助信息采集系統(tǒng)

"""

__tablename__ = 'lamp_result' # 定義表名

# 定義列名

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):

"""

引用該類別，輸出結(jié)果

:return:

"""

return str(self.__dict__)

# return ''.format(self.detect_result)

# 插入數(shù)據(jù)

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: 產(chǎn)品編號

:param record_time: 取原圖時間

:param lamp_color: 燈的顏色:1 2 3 4

:param detect_result: 檢測結(jié)果

:param old_pic_path: 原圖路徑

:param result_pic_path: 結(jié)果圖路徑

:return: 數(shù)據(jù)是否寫入成功

'''

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="張2", age=19),

# lamp_result(id=3, name="張3", age=20)

# ])

session.add(information_system_instance)

try:

session.commit() # 嘗試提交數(shù)據(jù)庫事務(wù)

# print('數(shù)據(jù)庫數(shù)據(jù)提交成功')

return {

"code": 200,

"status": True,

"message": "寫入數(shù)據(jù)庫成功",

}

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為True時，打印sql,可用于調(diào)試

# engine = create_engine(url, echo=False, encoding='utf-8', pool_size=5)

# sessionClass = sessionmaker(bind=engine)

# # 創(chuàng)建會話

# 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('數(shù)據(jù)成功')

if __name__ == '__main__':

result = insert_to_db(stu)

print(result)

3.數(shù)據(jù)函數(shù)調(diào)用

"""

Created on 19-10-31

@author: apple

@requirement:Anaconda 4.3.0 (64-bit) Python3.6

@description:調(diào)取函數(shù)基類

"""

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()

# 連接數(shù)據(jù)庫

# 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

# 創(chuàng)建session對象

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('數(shù)據(jù)成功')

# # 根據(jù)主建查詢數(shù)據(jù)

# result = session.query(DataSaveSystem).get(3)

# print(result.old_pic_path)

# # 查詢第一條

# result = session.query(DataSaveSystem).first()

# print(result) #打印對象屬性

# 查詢表關(guān)鍵字的數(shù)據(jù)

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()

希望本文所述對大家Python程序設(shè)計有所幫助。

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