SQLAlchemy
介紹
SQLAlchemy是一個基於Python實現的ORM框架。該框架創建在 DB API之上，使用關係對象映射進行數據庫操做，簡言之即是：將類和對象轉換成SQL，而後使用數據API執行SQL並獲取執行結果。html
安裝：python
pip install SQLAlchemy
組成部分：mysql
- Engine，框架的引擎
- Connection Pooling ，數據庫鏈接池
- Dialect，選擇鏈接數據庫的DB API種類
- Schema/Types，架構和類型
- SQL Exprression Language，SQL表達式語言
SQLAlchemy自己沒法操做數據庫，其必須以來pymsql等第三方插件，Dialect用於和數據API進行交流，根據配置文件的不一樣調用不一樣的數據庫API，從而實現對數據庫的操做，如：sql
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
使用
1.執行原生SQL
# -*- coding:utf-8 -*-
# /user/bin/python
# @Time : 2018/5/27 22:13
# @Author : liyongle
# @File : test.py
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/test?charset=utf8",
max_overflow=0, # 超過鏈接池大小外最多建立的鏈接
pool_size=5, # 鏈接池大小
pool_timeout=30, # 池中沒有線程最多等待的時間，不然報錯
pool_recycle=-1 # 多久以後對線程池中的線程進行一次鏈接的回收（重置）
)
def task(arg):
conn = engine.raw_connection()
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()
# -*- coding:utf-8 -*-
# /user/bin/python
# @Time : 2018/5/27 22:55
# @Author : liyongle
# @File : new_sql.py
#!/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()
# ##################### 單表示例 #########################
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)
# ##################### 一對多示例 #########################
class Hobby(Base):
__tablename__ = 'hobby'
id = Column(Integer, primary_key=True)
caption = Column(String(50), default='籃球')
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"))
# 與生成表結構無關，僅用於查詢方便
hobby = relationship("Hobby", backref='pers')
# ##################### 多對多示例 #########################
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)
# 與生成表結構無關，僅用於查詢方便
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():
"""
根據類建立數據庫表
:return:
"""
engine = create_engine(
"mysql+pymysql://root:123@127.0.0.1:3306/s6?charset=utf8",
max_overflow=0, # 超過鏈接池大小外最多建立的鏈接
pool_size=5, # 鏈接池大小
pool_timeout=30, # 池中沒有線程最多等待的時間，不然報錯
pool_recycle=-1 # 多久以後對線程池中的線程進行一次鏈接的回收（重置）
)
Base.metadata.create_all(engine)
def drop_db():
"""
根據類刪除數據庫表
:return:
"""
engine = create_engine(
"mysql+pymysql://root:123@127.0.0.1:3306/s6?charset=utf8",
max_overflow=0, # 超過鏈接池大小外最多建立的鏈接
pool_size=5, # 鏈接池大小
pool_timeout=30, # 池中沒有線程最多等待的時間，不然報錯
pool_recycle=-1 # 多久以後對線程池中的線程進行一次鏈接的回收（重置）
)
Base.metadata.drop_all(engine)
if __name__ == '__main__':
drop_db()
init_db()
# 建立多個表幷包含Fk、M2M關係
2.操做數據庫表
#!/usr/bin/env python
# -*- coding:utf-8 -*-
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)
##############方式一########################
Session = sessionmaker(bind=engine)
# 每次執行數據庫操做時，都須要建立一個session
session = Session()
# ############# 執行ORM操做 #############
obj1 = Users(name="alex1")
session.add(obj1)
# 提交事務
session.commit()
# 關閉session
session.close()
######################方式二####################
# 方式二：支持線程安全，爲每一個線程建立一個session
# - threading.Local
# - 惟一標識
# ScopedSession對象
# self.registry(), 加括號 建立session
# self.registry(), 加括號 建立session
# self.registry(), 加括號 建立session
from greenlet import getcurrent as get_ident
Session = sessionmaker(bind=engine)
session = scoped_session(Session,get_ident)
# session.add
# 操做
session.remove()
3.基本增刪改查示例
# -*- coding:utf-8 -*-
# /user/bin/python
# @Time : 2018/5/27 22:48
# @Author : liyongle
# @File : methods.py
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 new_sql 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()
"""
# ################ 刪除 ################
"""
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()
"""
# ################ 查詢 ################
"""
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.經常使用操做
# -*- coding:utf-8 -*-
# /user/bin/python
# @Time : 2018/5/27 22:52
# @Author : liyongle
# @File : some_sql.py
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 new_sql 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()
# 查詢
# 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語句
5.經常使用操做
# 條件
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()
# 分組
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()
# 連表
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()
# 組合
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()
6.基於relationship操做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
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='張三', hobby_id=3),
Person(name='李四', hobby_id=4),
])
person = Person(name='張九', hobby=Hobby(caption='姑娘'))
session.add(person)
hb = Hobby(caption='男人')
hb.pers = [Person(name='秋涼'), Person(name=''alex')]
session.add(hb)
session.commit()
"""
# 使用relationship正向查詢
"""
v = session.query(Person).first()
print(v.name)
print(v.hobby.caption)
"""
# 使用relationship反向查詢
"""
v = session.query(Hobby).first()
print(v.caption)
print(v.pers)
"""
session.close()
基於relationship操做ForeignKey
7.基於relationship操做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()
# 關聯子查詢
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
"""
# 查詢
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()
其餘
8. 基本增刪改查補充
#!/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)
#批量添加
session.add_all([
Users(name="wupeiqi"),
Users(name="alex"),
Hosts(name="c1.com"),
])
session.commit()
"""
# ################ 刪除 ################
"""
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) #字符串
session.query(Users).filter(Users.id > 0).update({"age": Users.age + 1}, synchronize_session="evaluate") #數字
session.commit()
"""
# ################ 查詢 ################
"""
r1 = session.query(Users).all()
r2 = session.query(Users.name.label('xx'), Users.age).all() #lable #as xx
r3 = session.query(Users).filter(Users.name == "alex").all()
r4 = session.query(Users).filter_by(name='alex').all() #若是裏面寫條件就用filter_by,和上面filter查詢是一回事，只是一種不一樣的方式
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() #查詢裏面若是有動態傳參的時候，吧它包在text裏面，:value,:name這樣的語法後面用.params來進行格式化
r7 = session.query(Users).from_statement(text("SELECT * FROM users where name=:name")).params(name='ed').all() #上面的這個方式也能夠用這一種 ，直接能夠進行SQL語句的查詢
"""
session.close()
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