Python3 之 MySQL操作模塊：pymsql和sqlachemy

本文轉載自查看原文 2017-09-13 23:37 1518

Python操作MySQL主要使用兩種方式：

原生模塊 pymsql
ORM框架 sqlachemy

pymsql

下載安裝

pip3 install pymysql

使用操作

1、執行SQL

 1 # -*- coding:utf-8 -*-
 2 
 3 import pymysql
 4   
 5 # 創建連接
 6 conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='123', db='t1')
 7 # 創建游標
 8 cursor = conn.cursor()
 9   
10 # 執行SQL，並返回收影響行數
11 effect_row = cursor.execute("update hosts set host = '1.1.1.2'")
12   
13 # 執行SQL，並返回受影響行數
14 #effect_row = cursor.execute("update hosts set host = '1.1.1.2' where nid > %s", (1,))
15   
16 # 執行SQL，並返回受影響行數
17 #effect_row = cursor.executemany("insert into hosts(host,color_id)values(%s,%s)", [("1.1.1.11",1),("1.1.1.11",2)])
18   
19   
20 # 提交，不然無法保存新建或者修改的數據
21 conn.commit()
22   
23 # 關閉游標
24 cursor.close()
25 # 關閉連接
26 conn.close()

2、獲取新創建數據自增ID

 1 # -*- coding:utf-8 -*-
 2 import pymysql
 3   
 4 conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='123', db='t1')
 5 cursor = conn.cursor()
 6 cursor.executemany("insert into hosts(host,color_id)values(%s,%s)", [("1.1.1.11",1),("1.1.1.11",2)])
 7 conn.commit()
 8 cursor.close()
 9 conn.close()
10   
11 # 獲取最新自增ID
12 new_id = cursor.lastrowid

3、獲取查詢數據

 1 # -*- coding:utf-8 -*-
 2 import pymysql
 3   
 4 conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='123', db='t1')
 5 cursor = conn.cursor()
 6 cursor.execute("select * from hosts")
 7   
 8 # 獲取第一行數據
 9 row_1 = cursor.fetchone()
10   
11 # 獲取前n行數據
12 # row_2 = cursor.fetchmany(3)
13 # 獲取所有數據
14 # row_3 = cursor.fetchall()
15   
16 conn.commit()
17 cursor.close()
18 conn.close()

注：在fetch數據時按照順序進行，可以使用cursor.scroll(num,mode)來移動游標位置，如：

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

4、fetch數據類型

　　關於默認獲取的數據是元祖類型，如果想要或者字典類型的數據，即：

 1 # -*- coding:utf-8 -*-
 2 import pymysql
 3   
 4 conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='123', db='t1')
 5   
 6 # 游標設置為字典類型
 7 cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)
 8 r = cursor.execute("call p1()")
 9   
10 result = cursor.fetchone()
11   
12 conn.commit()
13 cursor.close()
14 conn.close()

sqlachemy

sqlachemy是Python編程語言下的一款ORM框架，該框架建立在數據庫API之上，使用關系對象映射進行數據庫操作，簡言之便是：將對象轉換成SQL，然后使用數據API執行SQL並獲取執行結果。

安裝：

pip3 install sqlachemy

sqlachemy本身無法操作數據庫，其必須以來pymsql等第三方插件，Dialect用於和數據API進行交流，根據配置文件的不同調用不同的數據庫API，從而實現對數據庫的操作，如以pymsql為例：

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

一、內部處理

使用 Engine/ConnectionPooling/Dialect 進行數據庫操作，Engine使用ConnectionPooling連接數據庫，然后再通過Dialect執行SQL語句。

 1 # -*- coding:utf-8 -*-
 2 from sqlalchemy import create_engine
 3   
 4   
 5 engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/t1", max_overflow=5)
 6   
 7 # 執行SQL
 8 # cur = engine.execute(
 9 #     "INSERT INTO hosts (host, color_id) VALUES ('1.1.1.22', 3)"
10 # )
11   
12 # 新插入行自增ID
13 # cur.lastrowid
14   
15 # 執行SQL
16 # cur = engine.execute(
17 #     "INSERT INTO hosts (host, color_id) VALUES(%s, %s)",[('1.1.1.22', 3),('1.1.1.221', 3),]
18 # )
19   
20   
21 # 執行SQL
22 # cur = engine.execute(
23 #     "INSERT INTO hosts (host, color_id) VALUES (%(host)s, %(color_id)s)",
24 #     host='1.1.1.99', color_id=3
25 # )
26   
27 # 執行SQL
28 # cur = engine.execute('select * from hosts')
29 # 獲取第一行數據
30 # cur.fetchone()
31 # 獲取第n行數據
32 # cur.fetchmany(3)
33 # 獲取所有數據
34 # cur.fetchall()

二、ORM功能使用

使用 ORM/Schema Type/SQL Expression Language/Engine/ConnectionPooling/Dialect 所有組件對數據進行操作。根據類創建對象，對象轉換成SQL，執行SQL。

1、創建表

表結構 + 數據庫連接

 1 # -*- coding:utf-8 -*-
 2 from sqlalchemy.ext.declarative import declarative_base
 3 from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index
 4 from sqlalchemy.orm import sessionmaker, relationship
 5 from sqlalchemy import create_engine
 6 
 7 engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/t1", max_overflow=5)
 8 
 9 Base = declarative_base()
10 
11 # 創建單表
12 class Users(Base):
13     __tablename__ = 'users'
14     id = Column(Integer, primary_key=True)
15     name = Column(String(32))
16     extra = Column(String(16))
17 
18     __table_args__ = (
19     UniqueConstraint('id', 'name', name='uix_id_name'),
20         Index('ix_id_name', 'name', 'extra'),
21     )
22 
23     def __repr__(self):
24         return "%s-%s" %(self.id, self.name)
25 
26 # 一對多
27 class Favor(Base):
28     __tablename__ = 'favor'
29     nid = Column(Integer, primary_key=True)
30     caption = Column(String(50), default='red', unique=True)
31 
32     def __repr__(self):
33         return "%s-%s" %(self.nid, self.caption)
34 
35 class Person(Base):
36     __tablename__ = 'person'
37     nid = Column(Integer, primary_key=True)
38     name = Column(String(32), index=True, nullable=True)
39     favor_id = Column(Integer, ForeignKey("favor.nid"))
40     # 與生成表結構無關，僅用於查詢方便
41     favor = relationship("Favor", backref='pers')
42 
43 # 多對多
44 class ServerToGroup(Base):
45     __tablename__ = 'servertogroup'
46     nid = Column(Integer, primary_key=True, autoincrement=True)
47     server_id = Column(Integer, ForeignKey('server.id'))
48     group_id = Column(Integer, ForeignKey('group.id'))
49     group = relationship("Group", backref='s2g')
50     server = relationship("Server", backref='s2g')
51 
52 class Group(Base):
53     __tablename__ = 'group'
54     id = Column(Integer, primary_key=True)
55     name = Column(String(64), unique=True, nullable=False)
56     port = Column(Integer, default=22)
57     # group = relationship('Group',secondary=ServerToGroup,backref='host_list')
58 
59 
60 class Server(Base):
61     __tablename__ = 'server'
62 
63     id = Column(Integer, primary_key=True, autoincrement=True)
64     hostname = Column(String(64), unique=True, nullable=False)
65 
66 
67 
68 
69 def init_db():
70     Base.metadata.create_all(engine)
71 
72 
73 def drop_db():
74     Base.metadata.drop_all(engine)
75 
76 
77 Session = sessionmaker(bind=engine)
78 session = Session()

2、操作表

 1 # -*- coding:utf-8 -*-
 2  
 3 from sqlalchemy.ext.declarative import declarative_base
 4 from sqlalchemy import Column, Integer, String
 5 from sqlalchemy.orm import sessionmaker
 6 from sqlalchemy import create_engine
 7  
 8 engine = create_engine("mysql+mysqldb://root:123@127.0.0.1:3306/s11", max_overflow=5)
 9  
10 Base = declarative_base()
11  
12  
13 class User(Base):
14     __tablename__ = 'users'
15     id = Column(Integer, primary_key=True)
16     name = Column(String(50))
17  
18 # 尋找Base的所有子類，按照子類的結構在數據庫中生成對應的數據表信息
19 # Base.metadata.create_all(engine)
20  
21 Session = sessionmaker(bind=engine)
22 session = Session()
23  
24  
25 # ########## 增 ##########
26 # u = User(id=2, name='sb')
27 # session.add(u)
28 # session.add_all([
29 #     User(id=3, name='sb'),
30 #     User(id=4, name='sb')
31 # ])
32 # session.commit()
33  
34 # ########## 刪除 ##########
35 # session.query(User).filter(User.id > 2).delete()
36 # session.commit()
37  
38 # ########## 修改 ##########
39 # session.query(User).filter(User.id > 2).update({'cluster_id' : 0})
40 # session.commit()
41 # ########## 查 ##########
42 # ret = session.query(User).filter_by(name='sb').first()
43  
44 # ret = session.query(User).filter_by(name='sb').all()
45 # print (ret)
46  
47 # ret = session.query(User).filter(User.name.in_(['sb','bb'])).all()
48 # print (ret)
49  
50 # ret = session.query(User.name.label('name_label')).all()
51 # print (ret,type(ret))
52  
53 # ret = session.query(User).order_by(User.id).all()
54 # print (ret)
55  
56 # ret = session.query(User).order_by(User.id)[1:3]
57 # print (ret)
58 # session.commit()

免責聲明！

本站轉載的文章為個人學習借鑒使用，本站對版權不負任何法律責任。如果侵犯了您的隱私權益，請聯系本站郵箱yoyou2525@163.com刪除。

猜您在找 python3操作pymsql模塊 Python（九） Python 操作 MySQL 之 pysql 與 SQLAchemy Python自動化運維之18、Python操作 MySQL、pymysql、SQLAchemy python3 操作mysql Python3安裝mysql模塊 Python 操作 Mysql 模塊 python3操作mysql教程 python3 連接 mysql和mariadb的模塊 python中pymsql常用方法（1） python3 BeautifulSoup模塊