pyMysql

時間  2019-11-12
標籤 pymysql 欄目 MySQL 简体版
原文   原文鏈接

本篇對於Python操做MySQL主要使用兩種方式：html

  • 原生模塊 pymsql
  • ORM框架 SQLAchemy

pymsql

pymsql是Python中操做MySQL的模塊，其使用方法和MySQLdb幾乎相同。python

下載安裝

pip3 install pymysql

使用操做：mysql

1，執行sqlsql

#!/usr/bin/env python
# -*- coding:utf-8 -*-
import pymysql
  
# 建立鏈接
conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='123', db='t1')
# 建立遊標
cursor = conn.cursor()
  
# 執行SQL，並返回收影響行數
effect_row = cursor.execute("update hosts set host = '1.1.1.2'")
  
# 執行SQL，並返回受影響行數
#effect_row = cursor.execute("update hosts set host = '1.1.1.2' where nid > %s", (1,))
  
# 執行SQL，並返回受影響行數
#effect_row = cursor.executemany("insert into hosts(host,color_id)values(%s,%s)", [("1.1.1.11",1),("1.1.1.11",2)])
  
  
# 提交，否則沒法保存新建或者修改的數據
conn.commit()
  
# 關閉遊標
cursor.close()
# 關閉鏈接
conn.close()

2 獲取新建立自增id數據庫

#!/usr/bin/env python
# -*- coding:utf-8 -*-
import pymysql
  
conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='123', db='t1')
cursor = conn.cursor()
cursor.executemany("insert into hosts(host,color_id)values(%s,%s)", [("1.1.1.11",1),("1.1.1.11",2)])
conn.commit()
cursor.close()
conn.close()
  
# 獲取最新自增ID
new_id = cursor.lastrowid

3，獲取查詢數據編程

#!/usr/bin/env python
# -*- coding:utf-8 -*-
import pymysql
  
conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='123', db='t1')
cursor = conn.cursor()
cursor.execute("select * from hosts")
  
# 獲取第一行數據
row_1 = cursor.fetchone()
  
# 獲取前n行數據
# row_2 = cursor.fetchmany(3)
# 獲取全部數據
# row_3 = cursor.fetchall()
  
conn.commit()
cursor.close()
conn.close()

注：在fetch數據時按照順序進行，可使用cursor.scroll(num,mode)來移動遊標位置，如：session

  • cursor.scroll(1,mode='relative')  # 相對當前位置移動
  • cursor.scroll(2,mode='absolute') # 相對絕對位置移動

四、fetch數據類型app

　　關於默認獲取的數據是元祖類型，若是想要或者字典類型的數據，即：框架

#!/usr/bin/env python
# -*- coding:utf-8 -*-
import pymysql
  
conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='123', db='t1')
  
# 遊標設置爲字典類型
cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)
r = cursor.execute("call p1()")
  
result = cursor.fetchone()
  
conn.commit()
cursor.close()
conn.close()

SQLAchemy

SQLAlchemy是Python編程語言下的一款ORM框架，該框架創建在數據庫API之上，使用關係對象映射進行數據庫操做，簡言之即是：將對象轉換成SQL，而後使用數據API執行SQL並獲取執行結果。編程語言

安裝：

pip3 install SQLAlchemy

2、ORM功能使用

使用 ORM/Schema Type/SQL Expression Language/Engine/ConnectionPooling/Dialect 全部組件對數據進行操做。根據類建立對象，對象轉換成SQL，執行SQL。

 1，建立表

#!/usr/bin/env python
# -*- coding:utf-8 -*-
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
 
engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/t1", max_overflow=5)
 
Base = declarative_base()
 
# 建立單表
class Users(Base):
    __tablename__ = 'users'
    id = Column(Integer, primary_key=True)
    name = Column(String(32))
    extra = Column(String(16))
 
    __table_args__ = (
    UniqueConstraint('id', 'name', name='uix_id_name'),
        Index('ix_id_name', 'name', 'extra'),
    )
 
 
# 一對多
class Favor(Base):
    __tablename__ = 'favor'
    nid = Column(Integer, primary_key=True)
    caption = Column(String(50), default='red', unique=True)
 
 
class Person(Base):
    __tablename__ = 'person'
    nid = Column(Integer, primary_key=True)
    name = Column(String(32), index=True, nullable=True)
    favor_id = Column(Integer, ForeignKey("favor.nid"))
 
 
# 多對多
class Group(Base):
    __tablename__ = 'group'
    id = Column(Integer, primary_key=True)
    name = Column(String(64), unique=True, nullable=False)
    port = Column(Integer, default=22)
 
 
class Server(Base):
    __tablename__ = 'server'
 
    id = Column(Integer, primary_key=True, autoincrement=True)
    hostname = Column(String(64), unique=True, nullable=False)
 
 
class ServerToGroup(Base):
    __tablename__ = 'servertogroup'
    nid = Column(Integer, primary_key=True, autoincrement=True)
    server_id = Column(Integer, ForeignKey('server.id'))
    group_id = Column(Integer, ForeignKey('group.id'))
 
 
def init_db():
    Base.metadata.create_all(engine)
 
 
def drop_db():
    Base.metadata.drop_all(engine)
View Code

注：設置外檢的另外一種方式 ForeignKeyConstraint(['other_id'], ['othertable.other_id'])

#!/usr/bin/env/python
# -*- coding:utf-8 -*-

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

engine = create_engine('mysql+pymysql://root:@127.0.0.1:3306/aaa')
Base = declarative_base()

class Son(Base):
    __tablename__ ='son'
    id = Column(Integer,primary_key=True)
    name = Column(String(32))
    age = Column(String(16))

    father_id = Column(Integer,ForeignKey('father.id'))
class Father(Base):
    __tablename__ = 'father'

    id = Column(Integer,primary_key=True)
    name = Column(String(32))
    age = Column(String(16))
    son = relationship('Son',backref='father')

# Base.metadata.create_all(engine)
Session = sessionmaker(bind=engine)
session = Session()

# f1 = session .query(Father).filter_by(id=1).first()
# w3 = Son(name='yiduiduo 333',age=11)
# f1.son.append(w3)

# s1 = session.query(Son).filter_by(di=2).first()
# print(s1.father.name)
# session.add_all([w3])
# session.commit()

# ret = session.query(Father.name,Son.name).join().all()
# print(ret)


# f1 =Father(name = 'alvin',age = 50)
#
# w1 = Son(name='yiduiduo 111',age=10)
# w2 = Son(name='yiduiduo 222',age=11)
# f1.son =[w1,w2]
#
# session.add_all([f1,w1,w2])
# session.commit()
實例 一對多 
#!/usr/bin/env/python
# -*- coding:utf-8 -*-
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

engine = create_engine('mysql+pymysql://root:@127.0.0.1:3306/aaa?charset=utf8')  #創建鏈接

Base = declarative_base()  #建立ORM的基類

class Men_to_wemon(Base):  #建立關係映射表
    __tablename__ = 'men_to_wemon'   #定義數據表名
    nid = Column(Integer,primary_key=True)  #id 爲整數類型 而且爲主鍵
    men_id = Column(Integer,ForeignKey('men.id'))  #定義men_id 爲整數類型，綁定Men類id
    women_id = Column(Integer,ForeignKey('women.id'))  #定義women_id 爲整數類型，綁定women類id

class Men(Base):      #建立 男人表
    __tablename__ ='men'
    id = Column(Integer,primary_key=True)
    name = Column(String(32))
    age = Column(String(16))

    # gf = relationship('Women', secondary=Men_to_wemon.__table__)

class Women(Base):   #建立女人表
    __tablename__ ='women'
    id = Column(Integer,primary_key=True)
    name = Column(String(32))
    age = Column(String(16))
    bf = relationship('Men',secondary=Men_to_wemon.__table__,backref = 'gf') #定義關係映射 Men對應Men_to_wemon Women也對應Men_to_wemon
    # 一句話歸納了兩句對應關係，不須要再men表裏繼續定義關係了

Base.metadata.create_all(engine)
#經過激活sessionmaker 的__call__方法來return一個Session實例（Sesion類下提供了增刪改查的具體方法）
Session = sessionmaker(bind=engine)
session = Session()

m1 =Men(name = 'alex',age=12)
m2 =Men(name = 'wusir',age = 12)
w1 = Women(name = '如哈',age = 20)
w2 = Women(name = '安安',age = 20)
session.add_all([m1,m2,w1,w2,])  #添加全部的數據
session.commit()

t1 = Men_to_wemon(men_id =1,women_id=2)

m1 = session.query(Men).filter_by(id =2).first()
w1 = session.query(Women).all()
m1.gf = w1

session.add_all([m1,])
session.commit()
實例 多對多

 二、操做表

#!/usr/bin/env python
# -*- coding:utf-8 -*-
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

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

Base = declarative_base()

# 建立單表
class Users(Base):
    __tablename__ = 'users'
    id = Column(Integer, primary_key=True)
    name = Column(String(32))
    extra = Column(String(16))

    __table_args__ = (
    UniqueConstraint('id', 'name', name='uix_id_name'),
        Index('ix_id_name', 'name', 'extra'),
    )

    def __repr__(self):
        return "%s-%s" %(self.id, self.name)

# 一對多
class Favor(Base):
    __tablename__ = 'favor'
    nid = Column(Integer, primary_key=True)
    caption = Column(String(50), default='red', unique=True)

    def __repr__(self):
        return "%s-%s" %(self.nid, self.caption)

class Person(Base):
    __tablename__ = 'person'
    nid = Column(Integer, primary_key=True)
    name = Column(String(32), index=True, nullable=True)
    favor_id = Column(Integer, ForeignKey("favor.nid"))
    # 與生成表結構無關，僅用於查詢方便
    favor = relationship("Favor", backref='pers')

# 多對多
class ServerToGroup(Base):
    __tablename__ = 'servertogroup'
    nid = Column(Integer, primary_key=True, autoincrement=True)
    server_id = Column(Integer, ForeignKey('server.id'))
    group_id = Column(Integer, ForeignKey('group.id'))
    group = relationship("Group", backref='s2g')
    server = relationship("Server", backref='s2g')

class Group(Base):
    __tablename__ = 'group'
    id = Column(Integer, primary_key=True)
    name = Column(String(64), unique=True, nullable=False)
    port = Column(Integer, default=22)
    # group = relationship('Group',secondary=ServerToGroup,backref='host_list')


class Server(Base):
    __tablename__ = 'server'

    id = Column(Integer, primary_key=True, autoincrement=True)
    hostname = Column(String(64), unique=True, nullable=False)




def init_db():
    Base.metadata.create_all(engine)


def drop_db():
    Base.metadata.drop_all(engine)


Session = sessionmaker(bind=engine)
session = Session()
表結構+ 數據鏈接 
  •  增
obj = Users(name="alex0", extra='sb')
session.add(obj)
session.add_all([
    Users(name="alex1", extra='sb'),
    Users(name="alex2", extra='sb'),
])
session.commit()
View Code
  • 刪
session.query(Users).filter(Users.id > 2).delete()
session.commit()
View Code
  • 改
session.query(Users).filter(Users.id > 2).update({"name" : "099"})
session.query(Users).filter(Users.id > 2).update({Users.name: Users.name + "099"}, synchronize_session=False)
session.query(Users).filter(Users.id > 2).update({"num": Users.num + 1}, synchronize_session="evaluate")
session.commit()
View Code
  • 查
ret = session.query(Users).all()
ret = session.query(Users.name, Users.extra).all()
ret = session.query(Users).filter_by(name='alex').all()
ret = session.query(Users).filter_by(name='alex').first()
View Code
  • 條件
#　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()
View Code

更多功能參見文檔，猛擊這裏下載PDF

更多詳情參考博文：http://www.cnblogs.com/wupeiqi/articles/5713330.html

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