SQLAlchemy表操作和增删改查

一.SQLAlchemy介绍

SQLAlchemy是一个基于Python实现的ORM框架。该框架建立在 DB API之上，使用关系对象映射进行数据库操作，简言之便是：将类和对象转换成SQL，然后使用数据API执行SQL并获取执行结果。

安装sqlalchemy组件

pip3 install sqlalchemy

SQLAlchemy组件的内部原理

组成部分：

Engine，框架的引擎
Connection Pooling ，数据库连接池
Dialect，选择连接数据库的DB API种类
Schema/Types，架构和类型
SQL Exprression Language，SQL表达式语言，将创建的类翻译为SQl语言

SQLAlchemy本身无法操作数据库，其必须以来pymsql等第三方插件，Dialect用于和数据API进行交流，根据配置文件的不同调用不同的数据库API，从而实现对数据库的操作，如：

连接mysql 引擎 通过mysqldb 必须安装mysqldb
MySQL-Python

    mysql+mysqldb://<user>:<password>@<host>[:<port>]/<dbname>

pymysql

    mysql+pymysql://<username>:<password>@<host>/<dbname>[?<options>]

MySQL-Connector

    mysql+mysqlconnector://<user>:<password>@<host>[:<port>]/<dbname>

cx_Oracle

    oracle+cx_oracle://user:pass@host:port/dbname[?key=value&key=value...]

更多：http://docs.sqlalchemy.org/en/latest/dialects/index.html

二. 使用

1. 执行原生SQL语句

import threading

import sqlalchemy

from sqlalchemy import create_engine

engine = create_engine(

    "mysql+pymysql://root:123@127.0.0.1:3306/t1?charset=utf8",

    max_overflow=0,  # 超过连接池大小外最多创建的连接

    pool_size=5,  # 连接池大小

    pool_timeout=30,  # 池中没有可用线程在队列最多等待的时间，否则报错

    pool_recycle=-1  # 多久之后对线程池中的线程进行一次连接的回收（重置）

)

def task(arg):

    conn = engine.raw_connection()  # 原生连接

    cursor = conn.cursor()

    cursor.execute(

        "select * from test"

    )

    result = cursor.fetchall()

    cursor.close()

    conn.close()

for i in range(20):

    t = threading.Thread(target=task, args=(i,))

    t.start()

#!/usr/bin/env python

# -*- coding:utf-8 -*-

import time

import threading

import sqlalchemy

from sqlalchemy import create_engine

from sqlalchemy.engine.base import Engine

engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/t1", max_overflow=0, pool_size=5)

def task(arg):

    conn = engine.contextual_connect()

    with conn:

        cur = conn.execute(

            "select * from t1"

        )

        result = cur.fetchall()

        print(result)

for i in range(20):

    t = threading.Thread(target=task, args=(i,))

    t.start()

#!/usr/bin/env python

# -*- coding:utf-8 -*-

import time

import threading

import sqlalchemy

from sqlalchemy import create_engine

from sqlalchemy.engine.base import Engine

from sqlalchemy.engine.result import ResultProxy

engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/t1", max_overflow=0, pool_size=5)

def task(arg):

    cur = engine.execute("select * from t1")

    result = cur.fetchall()

    cur.close()

    print(result)

for i in range(20):

    t = threading.Thread(target=task, args=(i,))

    t.start()

注意: 查看连接 show status like 'Threads%';

2. ORM

a. 创建数据库表

#!/usr/bin/env python

# -*- coding:utf-8 -*-

import datetime

from sqlalchemy import create_engine

from sqlalchemy.ext.declarative import declarative_base

from sqlalchemy import Column, Integer, String, Text, ForeignKey, DateTime, UniqueConstraint, Index

Base = declarative_base()

class Users(Base):

    __tablename__ = 'users'

    id = Column(Integer, primary_key=True)

    name = Column(String(32), index=True, nullable=False)

    # email = Column(String(32), unique=True)

    # ctime = Column(DateTime, default=datetime.datetime.now)

    # extra = Column(Text, nullable=True)

    __table_args__ = (

        # UniqueConstraint('id', 'name', name='uix_id_name'),

        # Index('ix_id_name', 'name', 'email'),

    )

def init_db():

    """

    根据类创建数据库表

    :return:

    """

    engine = create_engine(

        "mysql+pymysql://root:123@127.0.0.1:3306/s6?charset=utf8",

        max_overflow=0,  # 超过连接池大小外最多创建的连接

        pool_size=5,  # 连接池大小

        pool_timeout=30,  # 池中没有线程最多等待的时间，否则报错

        pool_recycle=-1  # 多久之后对线程池中的线程进行一次连接的回收（重置）

    )

    Base.metadata.create_all(engine)

def drop_db():

    """

    根据类删除数据库表

    :return:

    """

    engine = create_engine(

        "mysql+pymysql://root:123@127.0.0.1:3306/s6?charset=utf8",

        max_overflow=0,  # 超过连接池大小外最多创建的连接

        pool_size=5,  # 连接池大小

        pool_timeout=30,  # 池中没有线程最多等待的时间，否则报错

        pool_recycle=-1  # 多久之后对线程池中的线程进行一次连接的回收（重置）

    )

    Base.metadata.drop_all(engine)

if __name__ == '__main__':

    drop_db()

    init_db()

创建单表

#!/usr/bin/env python

# -*- coding:utf-8 -*-

import datetime

from sqlalchemy import create_engine

from sqlalchemy.ext.declarative import declarative_base

from sqlalchemy import Column, Integer, String, Text, ForeignKey, DateTime, UniqueConstraint, Index

from sqlalchemy.orm import relationship

Base = declarative_base()

# ##################### 单表示例 #########################

class Users(Base):

    __tablename__ = 'users'

    id = Column(Integer, primary_key=True)

    name = Column(String(32), index=True)

    age = Column(Integer, default=18)

    email = Column(String(32), unique=True)

    ctime = Column(DateTime, default=datetime.datetime.now)

    extra = Column(Text, nullable=True)

    __table_args__ = (

        # UniqueConstraint('id', 'name', name='uix_id_name'),

        # Index('ix_id_name', 'name', 'extra'),

    )

class Hosts(Base):

    __tablename__ = 'hosts'

    id = Column(Integer, primary_key=True)

    name = Column(String(32), index=True)

    ctime = Column(DateTime, default=datetime.datetime.now)

# ##################### 一对多示例 #########################

class Hobby(Base):

    __tablename__ = 'hobby'

    id = Column(Integer, primary_key=True)

    caption = Column(String(50), default='篮球')

class Person(Base):

    __tablename__ = 'person'

    nid = Column(Integer, primary_key=True)

    name = Column(String(32), index=True, nullable=True)

    hobby_id = Column(Integer, ForeignKey("hobby.id"))

    # 与生成表结构无关，仅用于查询方便

    hobby = relationship("Hobby", backref='pers')

# ##################### 多对多示例 #########################

class Server2Group(Base):

    __tablename__ = 'server2group'

    id = Column(Integer, primary_key=True, autoincrement=True)

    server_id = Column(Integer, ForeignKey('server.id'))

    group_id = Column(Integer, ForeignKey('group.id'))

class Group(Base):

    __tablename__ = 'group'

    id = Column(Integer, primary_key=True)

    name = Column(String(64), unique=True, nullable=False)

    # 与生成表结构无关，仅用于查询方便

    servers = relationship('Server', secondary='server2group', backref='groups')

class Server(Base):

    __tablename__ = 'server'

    id = Column(Integer, primary_key=True, autoincrement=True)

    hostname = Column(String(64), unique=True, nullable=False)

def init_db():

    """

    根据类创建数据库表

    :return:

    """

    engine = create_engine(

        "mysql+pymysql://root:123@127.0.0.1:3306/s6?charset=utf8",

        max_overflow=0,  # 超过连接池大小外最多创建的连接

        pool_size=5,  # 连接池大小

        pool_timeout=30,  # 池中没有线程最多等待的时间，否则报错

        pool_recycle=-1  # 多久之后对线程池中的线程进行一次连接的回收（重置）

    )

    Base.metadata.create_all(engine)

def drop_db():

    """

    根据类删除数据库表

    :return:

    """

    engine = create_engine(

        "mysql+pymysql://root:123@127.0.0.1:3306/s6?charset=utf8",

        max_overflow=0,  # 超过连接池大小外最多创建的连接

        pool_size=5,  # 连接池大小

        pool_timeout=30,  # 池中没有线程最多等待的时间，否则报错

        pool_recycle=-1  # 多久之后对线程池中的线程进行一次连接的回收（重置）

    )

    Base.metadata.drop_all(engine)

if __name__ == '__main__':

    drop_db()

    init_db()

创建多个表并包含Fk、M2M关系

b. 操作数据库表

from sqlalchemy.orm import sessionmaker

from sqlalchemy import create_engine

from models import Users

engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/test", max_overflow=0, pool_size=5)

Session = sessionmaker(bind=engine)

# 每次执行数据库操作时，都需要创建一个session

session = Session()

# ############# 执行ORM操作 #############

obj1 = Users(name="alex1")

session.add(obj1)

# 提交事务

session.commit()

# 关闭session

session.close()

#!/usr/bin/env python

# -*- coding:utf-8 -*-

import time

import threading

from sqlalchemy.ext.declarative import declarative_base

from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index

from sqlalchemy.orm import sessionmaker, relationship

from sqlalchemy import create_engine

from db import Users

engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/s6", max_overflow=0, pool_size=5)

Session = sessionmaker(bind=engine)

def task(arg):

    session = Session()

    obj1 = Users(name="alex1")

    session.add(obj1)

    session.commit()

for i in range(10):

    t = threading.Thread(target=task, args=(i,))

    t.start()

多线程执行示例

#!/usr/bin/env python

# -*- coding:utf-8 -*-

import time

import threading

from sqlalchemy.ext.declarative import declarative_base

from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index

from sqlalchemy.orm import sessionmaker, relationship

from sqlalchemy import create_engine

from sqlalchemy.sql import text

from db import Users, Hosts

engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/s6", max_overflow=0, pool_size=5)

Session = sessionmaker(bind=engine)

session = Session()

# ################ 添加 ################

"""

obj1 = Users(name="wupeiqi")

session.add(obj1)

session.add_all([

    Users(name="wupeiqi"),

    Users(name="alex"),

    Hosts(name="c1.com"),

])

session.commit()

"""

# ################ 删除 ################

"""

session.query(Users).filter(Users.id > 2).delete()

session.commit()

"""

# ################ 修改 ################

"""

session.query(Users).filter(Users.id > 0).update({"name" : "099"})

session.query(Users).filter(Users.id > 0).update({Users.name: Users.name + "099"}, synchronize_session=False)

session.query(Users).filter(Users.id > 0).update({"age": Users.age + 1}, synchronize_session="evaluate")

session.commit()

"""

# ################ 查询 ################

"""

r1 = session.query(Users).all()

r2 = session.query(Users.name.label('xx'), Users.age).all()

r3 = session.query(Users).filter(Users.name == "alex").all()

r4 = session.query(Users).filter_by(name='alex').all()

r5 = session.query(Users).filter_by(name='alex').first()

r6 = session.query(Users).filter(text("id<:value and name=:name")).params(value=224, name='fred').order_by(Users.id).all()

r7 = session.query(Users).from_statement(text("SELECT * FROM users where name=:name")).params(name='ed').all()

"""

session.close()

基本增删改查示例

#　条件

ret = session.query(Users).filter_by(name='alex').all()

ret = session.query(Users).filter(Users.id > 1, Users.name == 'eric').all()

ret = session.query(Users).filter(Users.id.between(1, 3), Users.name == 'eric').all()

ret = session.query(Users).filter(Users.id.in_([1,3,4])).all()

ret = session.query(Users).filter(~Users.id.in_([1,3,4])).all()

ret = session.query(Users).filter(Users.id.in_(session.query(Users.id).filter_by(name='eric'))).all()

from sqlalchemy import and_, or_

ret = session.query(Users).filter(and_(Users.id > 3, Users.name == 'eric')).all()

ret = session.query(Users).filter(or_(Users.id < 2, Users.name == 'eric')).all()

ret = session.query(Users).filter(

    or_(

        Users.id < 2,

        and_(Users.name == 'eric', Users.id > 3),

        Users.extra != ""

    )).all()

# 通配符

ret = session.query(Users).filter(Users.name.like('e%')).all()

ret = session.query(Users).filter(~Users.name.like('e%')).all()

# 限制

ret = session.query(Users)[1:2]

# 排序

ret = session.query(Users).order_by(Users.name.desc()).all()

ret = session.query(Users).order_by(Users.name.desc(), Users.id.asc()).all()

# 分组

from sqlalchemy.sql import func

ret = session.query(Users).group_by(Users.extra).all()

ret = session.query(

    func.max(Users.id),

    func.sum(Users.id),

    func.min(Users.id)).group_by(Users.name).all()

ret = session.query(

    func.max(Users.id),

    func.sum(Users.id),

    func.min(Users.id)).group_by(Users.name).having(func.min(Users.id) >2).all()

# 连表

ret = session.query(Users, Favor).filter(Users.id == Favor.nid).all()

ret = session.query(Person).join(Favor).all()

ret = session.query(Person).join(Favor, isouter=True).all()

# 组合

q1 = session.query(Users.name).filter(Users.id > 2)

q2 = session.query(Favor.caption).filter(Favor.nid < 2)

ret = q1.union(q2).all()

q1 = session.query(Users.name).filter(Users.id > 2)

q2 = session.query(Favor.caption).filter(Favor.nid < 2)

ret = q1.union_all(q2).all()

常用操作

#!/usr/bin/env python

# -*- coding:utf-8 -*-

import time

import threading

from sqlalchemy.ext.declarative import declarative_base

from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index

from sqlalchemy.orm import sessionmaker, relationship

from sqlalchemy import create_engine

from sqlalchemy.sql import text

from sqlalchemy.engine.result import ResultProxy

from db import Users, Hosts

engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/s6", max_overflow=0, pool_size=5)

Session = sessionmaker(bind=engine)

session = Session()

# 查询

# cursor = session.execute('select * from users')

# result = cursor.fetchall()

# 添加

cursor = session.execute('insert into users(name) values(:value)',params={"value":'wupeiqi'})

session.commit()

print(cursor.lastrowid)

session.close()

原生SQL语句

#!/usr/bin/env python

# -*- coding:utf-8 -*-

import time

import threading

from sqlalchemy.ext.declarative import declarative_base

from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index

from sqlalchemy.orm import sessionmaker, relationship

from sqlalchemy import create_engine

from sqlalchemy.sql import text

from sqlalchemy.engine.result import ResultProxy

from db import Users, Hosts, Hobby, Person

engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/s6?charset=utf8", max_overflow=0, pool_size=5)

Session = sessionmaker(bind=engine)

session = Session()

# 添加

"""

session.add_all([

    Hobby(caption='乒乓球'),

    Hobby(caption='羽毛球'),

    Person(name='张三', hobby_id=3),

    Person(name='李四', hobby_id=4),

])

person = Person(name='张九', hobby=Hobby(caption='姑娘'))

session.add(person)

hb = Hobby(caption='人妖')

hb.pers = [Person(name='文飞'), Person(name='博雅')]

session.add(hb)

session.commit()

"""

# 使用relationship正向查询

"""

v = session.query(Person).first()

print(v.name)

print(v.hobby.caption)

"""

# 使用relationship反向查询

"""

v = session.query(Hobby).first()

print(v.caption)

print(v.pers)

"""

session.close()

基于relationship操作ForeignKey

#!/usr/bin/env python

# -*- coding:utf-8 -*-

import time

import threading

from sqlalchemy.ext.declarative import declarative_base

from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index

from sqlalchemy.orm import sessionmaker, relationship

from sqlalchemy import create_engine

from sqlalchemy.sql import text

from sqlalchemy.engine.result import ResultProxy

from db import Users, Hosts, Hobby, Person, Group, Server, Server2Group

engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/s6?charset=utf8", max_overflow=0, pool_size=5)

Session = sessionmaker(bind=engine)

session = Session()

# 添加

"""

session.add_all([

    Server(hostname='c1.com'),

    Server(hostname='c2.com'),

    Group(name='A组'),

    Group(name='B组'),

])

session.commit()

s2g = Server2Group(server_id=1, group_id=1)

session.add(s2g)

session.commit()

gp = Group(name='C组')

gp.servers = [Server(hostname='c3.com'),Server(hostname='c4.com')]

session.add(gp)

session.commit()

ser = Server(hostname='c6.com')

ser.groups = [Group(name='F组'),Group(name='G组')]

session.add(ser)

session.commit()

"""

# 使用relationship正向查询

"""

v = session.query(Group).first()

print(v.name)

print(v.servers)

"""

# 使用relationship反向查询

"""

v = session.query(Server).first()

print(v.hostname)

print(v.groups)

"""

session.close()

基于relationship操作m2m

#!/usr/bin/env python

# -*- coding:utf-8 -*-

import time

import threading

from sqlalchemy.ext.declarative import declarative_base

from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index

from sqlalchemy.orm import sessionmaker, relationship

from sqlalchemy import create_engine

from sqlalchemy.sql import text, func

from sqlalchemy.engine.result import ResultProxy

from db import Users, Hosts, Hobby, Person, Group, Server, Server2Group

engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/s6?charset=utf8", max_overflow=0, pool_size=5)

Session = sessionmaker(bind=engine)

session = Session()

# 关联子查询

subqry = session.query(func.count(Server.id).label("sid")).filter(Server.id == Group.id).correlate(Group).as_scalar()

result = session.query(Group.name, subqry)

"""

SELECT `group`.name AS group_name, (SELECT count(server.id) AS sid

FROM server

WHERE server.id = `group`.id) AS anon_1

FROM `group`

"""

# 原生SQL

"""

# 查询

cursor = session.execute('select * from users')

result = cursor.fetchall()

# 添加

cursor = session.execute('insert into users(name) values(:value)',params={"value":'wupeiqi'})

session.commit()

print(cursor.lastrowid)

"""

session.close()

其他

SQLAlchemy表操作和增删改查的更多相关文章

Django---ORM简介丶单表操作丶增删改查
一丶ORM简介 MVC或者MVC框架中包括一个重要的部分,就是ORM,它实现了数据模型与数据库的解耦,即数据模型的设计不需要依赖于特定的数据库,通过简单的配置就可以轻松更换数据库,这极大的减轻了开发人 ...
Django【第6篇】：Django之ORM单表操作（增删改查）
django之数据库表的单表查询一.添加表记录对于单表有两种方式 # 添加数据的两种方式 # 方式一:实例化对象就是一条表记录 Frank_obj = models.Student(name =& ...
SQLAlchemy02 /SQLAlchemy对数据的增删改查操作、属性常用数据类型详解
SQLAlchemy02 /SQLAlchemy对数据的增删改查操作.属性常用数据类型详解目录 SQLAlchemy02 /SQLAlchemy对数据的增删改查操作.属性常用数据类型详解 1.用se ...
SQLAlchemy（二)：SQLAlchemy对数据的增删改查操作、属性常用数据类型详解
SQLAlchemy02 /SQLAlchemy对数据的增删改查操作.属性常用数据类型详解目录 SQLAlchemy02 /SQLAlchemy对数据的增删改查操作.属性常用数据类型详解 1.用se ...
js操作indexedDB增删改查示例
js操作indexedDB增删改查示例 if ('indexedDB' in window) { // 如果数据库不存在则创建,如果存在但是version更大,会自动升级不会复制原来的版本 var r ...
django-orm框架表单的增删改查
08.14自我总结 django-orm框架一.orm基本配置 1.创建django项目命令行:cmd先去到django创建目录,然后输入django-admin startproject dja ...
Django框架之第二篇--app注册、静态文件配置、form表单提交、pycharm连接数据库、django使用mysql数据库、表字段的增删改查、表数据的增删改查
本节知识点大致为:静态文件配置.form表单提交数据后端如何获取.request方法.pycharm连接数据库,django使用mysql数据库.表字段的增删改查.表数据的增删改查一.创建app,创 ...
MySQL数据分析（16）— 数据操作之增删改查
前面我们说学习MySQL要从三个层面,四大逻辑来学,三个层面就是库层面,表层面和数据层面对吧,数据库里放数据表,表里放数据是吧,大家可以回忆PPT中jacky的这图,我们已经学完了库层面和表层面,从本 ...
Online Coding开发模式 (通过在线配置实现一个表模型的增删改查功能，无需写任何代码)
JEECG 智能开发平台. 开发模式由代码生成器转变为Online Coding模式 (通过在线配置实现一个表模型的增删改查功能,无需一行代码,支持用户自定义 ...

随机推荐

Springboot的默认定时任务——Scheduled注解
本博客参考博文地址. 1.pom依赖: 引入springboot starter包即可 <dependencies> <dependency> <groupId>o ...
java多线程编程核心技术——第七章补漏拾遗
本章主要知识点: 1)线程组的使用 2)如何切换线程状态 3)SimpleDateFormat类与多线程的解决方法 4)如何处理线程异常. 这本书基本来到了终点,其实在第四章来说,核心(基础)的线程知 ...
使用Spring访问Mongodb的方法大全——Spring Data MongoDB查询指南
1.概述 Spring Data MongoDB 是Spring框架访问mongodb的神器,借助它可以非常方便的读写mongo库.本文介绍使用Spring Data MongoDB来访问mongod ...
为什么要使用消息认证码（MAC）而非对称密钥？
问题: 看了消息认证码的介绍后,小丽心想"如果用对称密码将消息加密后再发送的话,是不是就不需要消息认证码了呢?"原因有下: 1.对称密码的密文只有使用和加密时相同的密钥才能正确解密 ...
docker容器自动退出的问题
如果用了一段时间的docker就会发现,我们的容器经常用了一段时间就自动退出了,docker ps已经找不到了,在docker ps -a里面了,然后我们docker start containerI ...
封装一个button上带图片的，图片在上，文字在下的按钮
#import "CJShoppingDetailButton.h" @implementation CJShoppingDetailButton - (void)layoutSu ...
【java】内存流：java.io.ByteArrayInputStream、java.io.ByteArrayOutputStream、java.io.CharArrayReader、java.io.CharArrayWriter
package 内存流; import java.io.ByteArrayInputStream; import java.io.ByteArrayOutputStream; import java. ...
iOS NSString 文本不同的颜色标题+文本字体大小行间距／删除不需要的字符／以及自适应高度
#import <Foundation/Foundation.h> @interface TextsForRow : NSObject @property(nonatomic,copy)N ...
ABP PUT、DELETE请求错误405.0 - Method Not Allowed 因为使用了无效方法(HTTP 谓词) 引发客户端错误 No 'Access-Control-Allow-Origin' header is present on the requested resource
先请检查是否是跨域配置问题,请参考博客:http://www.cnblogs.com/donaldtdz/p/7882225.html 一.问题描述 ABP angular前端部署后,查询,新增都没问 ...
sed使用范例
本文同时发表在https://github.com/zhangyachen/zhangyachen.github.io/issues/32 记录下sed编译器的常见使用方法. sed编辑器基于输入到命 ...