SQLAlchemy相关文档
目录
参考文档
一.执行原生SQL语句
1.实例一
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?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）
)
def task(arg):
conn = engine.raw_connection()
cursor = conn.cursor()
cursor.execute(
"select * from t1"
)
result = cursor.fetchall()
cursor.close()
conn.close()
for i in range(20):
t = threading.Thread(target=task, args=(i,))
t.start()
2.实例二
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()
2.实例三
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()
二.ORM操作
1.创建数据库表
(1)创建单表
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()
(2)创建多个表并包含FK、M2M关系
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()
2.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/s6", 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()
(1)基于scoped_session实现线程安全
from sqlalchemy.orm import sessionmaker
from sqlalchemy import create_engine
from sqlalchemy.orm import scoped_session
from models 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)
"""
# 线程安全，基于本地线程实现每个线程用同一个session
# 特殊的：scoped_session中有原来方法的Session中的一下方法：
public_methods = (
'__contains__', '__iter__', 'add', 'add_all', 'begin', 'begin_nested',
'close', 'commit', 'connection', 'delete', 'execute', 'expire',
'expire_all', 'expunge', 'expunge_all', 'flush', 'get_bind',
'is_modified', 'bulk_save_objects', 'bulk_insert_mappings',
'bulk_update_mappings',
'merge', 'query', 'refresh', 'rollback',
'scalar'
)
"""
session = scoped_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()
(2)多线程执行示例
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()
(3)基本增删改查示例
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()
(4)常用操作
# 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()
(5)原生SQL语句
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()
(6)基于relationship操作ForeignKey
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()
(7)基于relationship操作m2m
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()
(8)其他
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()
SQLAlchemy相关文档的更多相关文章
- 20190131 经验总结：如何从rst文件编译出自己的sqlalchemy的文档
20190131 经验总结:如何编译sqlalchemy的文档 起因 www.sqlalchemy.org官网上不去了,不管是直接上,还是用代理都不行. sqlalchemy属于常用工具,看不到官方的 ...
- dotNET跨平台相关文档整理
一直在从事C#开发的相关技术工作,从C# 1.0一路用到现在的C# 6.0, 通常情况下被局限于Windows平台,Mono项目把我们C#程序带到了Windows之外的平台,在工作之余花了很多时间在M ...
- Mybatis-Generator 自动生成Dao、Model、Mapping相关文档
最近在学习mybatis,结果在写Mapping的映射文件时insert语句一直报错,于是想看看标准的映射文件是什么样.百度到Mybatis-Generator 自动生成Dao.Model.Mappi ...
- VLC的相关文档以及javascript接口
参看下面链接:VLC相关文档
- dotNET跨平台相关文档
dotNET跨平台相关文档整理 一直在从事C#开发的相关技术工作,从C# 1.0一路用到现在的C# 6.0, 通常情况下被局限于Windows平台,Mono项目把我们C#程序带到了Windows之外的 ...
- 大数据相关文档&Api下载
IT相关文档&Api下载(不断更新中) 下载地址:https://download.csdn.net/user/qq_42797237/uploads 如有没有你需要的API,可和我留言,留下 ...
- rn相关文档
RN相关文档: rn文档:https://reactnative.cn/ mbox文档:https://cn.mobx.js.org/ es6文档:http://es6.ruanyifeng.com/ ...
- OSS阿里云相关文档
OSS阿里云相关文档 oss文档链接
- hugo官方相关文档地址
+++ date="2020-10-17" title="hugo官方相关文档地址" tags=["hugo"] categories=[& ...
随机推荐
- Mongodb 查询优化（慢查询Profiling）
开启慢查询Profiling Profiling级别说明 0:关闭,不收集任何数据. 1:收集慢查询数据,默认是100毫秒. 2:收集所有数据 1.通过修改配置文件开启Profiling 修改启动mo ...
- 解决update-apt-xapi占用资源过高的问题
最近云主机出现了个报错,查看系统日志发现是update-apt-xapi任务占用资源过高,甚至内存占完了无法开辟内存 云主机:Ubuntu 14.04.5 LTS update-apt-xapi是干嘛 ...
- Web API 跨域
1. NuGet下载## microsoft.aspnet.webapi.cors 2 . Web API 路由中 config.EnableCors(new EnableCorsAttribute( ...
- POI2010 Bridges
好题\(Q\omega Q\) 我们考虑这个东西要求最大值最小,显然一眼二分答案对吧. 问题在于如何\(check\),我们二分答案之后把问题转换成了混合图如何求欧拉回路. 考虑欧拉回路的性质,每一个 ...
- ListView / GirdView Adpater的getView方法，首项多次调用
通过Adapter为AbslistView提供内容是一个常见的做法:在ListView或者GridView的Adapter中的getView()方法中,加入一行日志,看getView()被调用的情况 ...
- nodejs配置QQ企业邮箱
安装模块 npm install -g nodemailer npm install -g nodemailer-smtp-transport 代码示例 var nodemailer = requir ...
- 使用WebSocket实现服务端和客户端的通信
开发中经常会有这样的使用场景.如某个用户在一个数据上做了xx操作, 与该数据相关的用户在线上的话,需要实时接收到一条信息. 这种可以使用WebSocket来实现. 另外,对于消息,可以定义一个类进行固 ...
- Mininet系列实验（二）：Mininet可视化应用
1 实验目的 该实验通过Mininet学习miniedit可视化操作,可直接在界面上编辑任意想要的拓扑,生成python自定义拓扑脚本,简单方便.在实验过程中,可以了解以下方面的知识: Miniedi ...
- DELPHI解析JSON格式化的日期
DELPHI解析JSON格式化的日期 json返回的日期是 /Date(1560355200000)/ 这样的格式. 这个1560355200000,是指1970年以后的秒数. DELPHI如何解析这 ...
- Uploadifive 上传'fileType'格式如何限制？
Uploadifive: 'fileType':[ "application/pdf", "application/msword", "applica ...