mysql数据库----python操作mysql ------pymysql和SQLAchemy
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•
2025-01-07 13:51:38
本篇对于Python操作MySQL主要使用两种方式：
- 原生模块 pymsql
- ORM框架 SQLAchemy
一、pymysql
pymsql是Python中操作MySQL的模块，其使用方法和MySQLdb几乎相同。
下载安装
使用操作
1、执行SQL
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1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 import pymysql
4
5 # 创建连接
6 conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='123', db='t1')
7 # 创建游标
8 cursor = conn.cursor()
9
10 # 执行SQL，并返回收影响行数
11 effect_row = cursor.execute("update hosts set host = '1.1.1.2'")
12
13 # 执行SQL，并返回受影响行数
14 #effect_row = cursor.execute("update hosts set host = '1.1.1.2' where nid > %s", (1,))
15
16 # 执行SQL，并返回受影响行数
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，不然无法保存新建或者修改的数据
21 conn.commit()
22
23 # 关闭游标
24 cursor.close()
25 # 关闭连接
26 conn.close()
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2、获取新创建数据自增ID
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1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 import pymysql
4
5 conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='123', db='t1')
6 cursor = conn.cursor()
7 cursor.executemany("insert into hosts(host,color_id)values(%s,%s)", [("1.1.1.11",1),("1.1.1.11",2)])
8 conn.commit()
9 cursor.close()
10 conn.close()
11
12 # 获取最新自增ID
13 new_id = cursor.lastrowid
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3、获取查询数据
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1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 import pymysql
4
5 conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='123', db='t1')
6 cursor = conn.cursor()
7 cursor.execute("select * from hosts")
8
9 # 获取第一行数据
10 row_1 = cursor.fetchone()
11
12 # 获取前n行数据
13 # row_2 = cursor.fetchmany(3)
14 # 获取所有数据
15 # row_3 = cursor.fetchall()
16
17 conn.commit()
18 cursor.close()
19 conn.close()
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注：在fetch数据时按照顺序进行，可以使用cursor.scroll(num,mode)来移动游标位置，如：
- cursor.scroll(1,mode='relative') # 相对当前位置移动
- cursor.scroll(2,mode='absolute') # 相对绝对位置移动
4、fetch数据类型
关于默认获取的数据是元祖类型，如果想要或者字典类型的数据，即：
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1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 import pymysql
4
5 conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='123', db='t1')
6
7 # 游标设置为字典类型
8 cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)
9 r = cursor.execute("call p1()")
10
11 result = cursor.fetchone()
12
13 conn.commit()
14 cursor.close()
15 conn.close()
View Code
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1 作业：
2 参考表结构：
3 用户类型
4
5 用户信息
6
7 权限
8
9 用户类型&权限
10 功能：
11
12 # 登陆、注册、找回密码
13 # 用户管理
14 # 用户类型
15 # 权限管理
16 # 分配权限
17
18 特别的：程序仅一个可执行文件
练习题
注意： (python代码操作数据库)
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1 import pymysql
2
3 user = input("username:")
4 pwd = input("password:")
5
6 conn = pymysql.connect(host="localhost",user='root',password='',database="db666")
7 cursor = conn.cursor()
8 sql = "select * from userinfo where username='%s' and password='%s'" %(user,pwd) #这段代码提到了注入问题，直接拼接会被他人任意登入，风险很大，所以不能这样写！
9 # select * from userinfo where username='uu' or 1=1 -- ' and password='%s' #这里就是利用了注入问题登入了数据库
10 cursor.execute(sql)
11 result = cursor.fetchone()
12 cursor.close()
13 conn.close()
14
15 if result:
16 print('登录成功')
17 else:
18 print('登录失败')
sql注入问题（这种写法错误）
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1 import pymysql
2
3 user = input("username:")
4 pwd = input("password:")
5
6 conn = pymysql.connect(host="localhost",user='root',password='',database="db666")
7 cursor = conn.cursor()
8 sql = "select * from userinfo where username=%s and password=%s"
9 cursor.execute(sql,user,pwd)
10 # cursor.execute(sql,[user,pwd])
11 # cursor.execute(sql,{'u':user,'p':pwd})
12 result = cursor.fetchone()
13 cursor.close()
14 conn.close()
15 if result:
16 print('登录成功')
17 else:
18 print('登录失败')
正确的写法
二、SQLAchemy
SQLAlchemy是Python编程语言下的一款ORM框架，该框架建立在数据库API之上，使用关系对象映射进行数据库操作，简言之便是：将对象转换成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：
1 MySQL-Python
2 mysql+mysqldb://<user>:<password>@<host>[:<port>]/<dbname>
3
4 pymysql
5 mysql+pymysql://<username>:<password>@<host>/<dbname>[?<options>]
6
7 MySQL-Connector
8 mysql+mysqlconnector://<user>:<password>@<host>[:<port>]/<dbname>
9
10 cx_Oracle
11 oracle+cx_oracle://user:pass@host:port/dbname[?key=value&key=value...]
12
13 更多详见：http://docs.sqlalchemy.org/en/latest/dialects/index.html
一、内部处理
使用 Engine/ConnectionPooling/Dialect 进行数据库操作，Engine使用ConnectionPooling连接数据库，然后再通过Dialect执行SQL语句。
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1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 from sqlalchemy import create_engine
4
5
6 engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/t1", max_overflow=5)
7
8 # 执行SQL
9 # cur = engine.execute(
10 # "INSERT INTO hosts (host, color_id) VALUES ('1.1.1.22', 3)"
11 # )
12
13 # 新插入行自增ID
14 # cur.lastrowid
15
16 # 执行SQL
17 # cur = engine.execute(
18 # "INSERT INTO hosts (host, color_id) VALUES(%s, %s)",[('1.1.1.22', 3),('1.1.1.221', 3),]
19 # )
20
21
22 # 执行SQL
23 # cur = engine.execute(
24 # "INSERT INTO hosts (host, color_id) VALUES (%(host)s, %(color_id)s)",
25 # host='1.1.1.99', color_id=3
26 # )
27
28 # 执行SQL
29 # cur = engine.execute('select * from hosts')
30 # 获取第一行数据
31 # cur.fetchone()
32 # 获取第n行数据
33 # cur.fetchmany(3)
34 # 获取所有数据
35 # cur.fetchall()
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二、ORM功能使用
使用 ORM/Schema Type/SQL Expression Language/Engine/ConnectionPooling/Dialect 所有组件对数据进行操作。根据类创建对象，对象转换成SQL，执行SQL。
1、创建表
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1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 from sqlalchemy.ext.declarative import declarative_base
4 from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index
5 from sqlalchemy.orm import sessionmaker, relationship
6 from sqlalchemy import create_engine
7
8 engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/t1", max_overflow=5)
9
10 Base = declarative_base()
11
12 # 创建单表
13 class Users(Base):
14 __tablename__ = 'users'
15 id = Column(Integer, primary_key=True)
16 name = Column(String(32))
17 extra = Column(String(16))
18
19 __table_args__ = (
20 UniqueConstraint('id', 'name', name='uix_id_name'),
21 Index('ix_id_name', 'name', 'extra'),
22 )
23
24
25 # 一对多
26 class Favor(Base):
27 __tablename__ = 'favor'
28 nid = Column(Integer, primary_key=True)
29 caption = Column(String(50), default='red', unique=True)
30
31
32 class Person(Base):
33 __tablename__ = 'person'
34 nid = Column(Integer, primary_key=True)
35 name = Column(String(32), index=True, nullable=True)
36 favor_id = Column(Integer, ForeignKey("favor.nid"))
37
38
39 # 多对多
40 class Group(Base):
41 __tablename__ = 'group'
42 id = Column(Integer, primary_key=True)
43 name = Column(String(64), unique=True, nullable=False)
44 port = Column(Integer, default=22)
45
46
47 class Server(Base):
48 __tablename__ = 'server'
49
50 id = Column(Integer, primary_key=True, autoincrement=True)
51 hostname = Column(String(64), unique=True, nullable=False)
52
53
54 class ServerToGroup(Base):
55 __tablename__ = 'servertogroup'
56 nid = Column(Integer, primary_key=True, autoincrement=True)
57 server_id = Column(Integer, ForeignKey('server.id'))
58 group_id = Column(Integer, ForeignKey('group.id'))
59
60
61 def init_db():
62 Base.metadata.create_all(engine)
63
64
65 def drop_db():
66 Base.metadata.drop_all(engine)
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注：设置外检的另一种方式 ForeignKeyConstraint(['other_id'], ['othertable.other_id'])
2、操作表
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1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 from sqlalchemy.ext.declarative import declarative_base
4 from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index
5 from sqlalchemy.orm import sessionmaker, relationship
6 from sqlalchemy import create_engine
7
8 engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/t1", max_overflow=5)
9
10 Base = declarative_base()
11
12 # 创建单表
13 class Users(Base):
14 __tablename__ = 'users'
15 id = Column(Integer, primary_key=True)
16 name = Column(String(32))
17 extra = Column(String(16))
18
19 __table_args__ = (
20 UniqueConstraint('id', 'name', name='uix_id_name'),
21 Index('ix_id_name', 'name', 'extra'),
22 )
23
24 def __repr__(self):
25 return "%s-%s" %(self.id, self.name)
26
27 # 一对多
28 class Favor(Base):
29 __tablename__ = 'favor'
30 nid = Column(Integer, primary_key=True)
31 caption = Column(String(50), default='red', unique=True)
32
33 def __repr__(self):
34 return "%s-%s" %(self.nid, self.caption)
35
36 class Person(Base):
37 __tablename__ = 'person'
38 nid = Column(Integer, primary_key=True)
39 name = Column(String(32), index=True, nullable=True)
40 favor_id = Column(Integer, ForeignKey("favor.nid"))
41 # 与生成表结构无关，仅用于查询方便
42 favor = relationship("Favor", backref='pers')
43
44 # 多对多
45 class ServerToGroup(Base):
46 __tablename__ = 'servertogroup'
47 nid = Column(Integer, primary_key=True, autoincrement=True)
48 server_id = Column(Integer, ForeignKey('server.id'))
49 group_id = Column(Integer, ForeignKey('group.id'))
50 group = relationship("Group", backref='s2g')
51 server = relationship("Server", backref='s2g')
52
53 class Group(Base):
54 __tablename__ = 'group'
55 id = Column(Integer, primary_key=True)
56 name = Column(String(64), unique=True, nullable=False)
57 port = Column(Integer, default=22)
58 # group = relationship('Group',secondary=ServerToGroup,backref='host_list')
59
60
61 class Server(Base):
62 __tablename__ = 'server'
63
64 id = Column(Integer, primary_key=True, autoincrement=True)
65 hostname = Column(String(64), unique=True, nullable=False)
66
67
68
69
70 def init_db():
71 Base.metadata.create_all(engine)
72
73
74 def drop_db():
75 Base.metadata.drop_all(engine)
76
77
78 Session = sessionmaker(bind=engine)
79 session = Session()
80
81 表结构 + 数据库连接
表结构+数据库
增
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1 obj = Users(name="alex0", extra='sb')
2 session.add(obj)
3 session.add_all([
4 Users(name="alex1", extra='sb'),
5 Users(name="alex2", extra='sb'),
6 ])
7 session.commit()
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删
session.query(Users).filter(Users.id > 2).delete()
session.commit()
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()
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()
其他
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1 # 条件
2 ret = session.query(Users).filter_by(name='alex').all()
3 ret = session.query(Users).filter(Users.id > 1, Users.name == 'eric').all()
4 ret = session.query(Users).filter(Users.id.between(1, 3), Users.name == 'eric').all()
5 ret = session.query(Users).filter(Users.id.in_([1,3,4])).all()
6 ret = session.query(Users).filter(~Users.id.in_([1,3,4])).all()
7 ret = session.query(Users).filter(Users.id.in_(session.query(Users.id).filter_by(name='eric'))).all()
8 from sqlalchemy import and_, or_
9 ret = session.query(Users).filter(and_(Users.id > 3, Users.name == 'eric')).all()
10 ret = session.query(Users).filter(or_(Users.id < 2, Users.name == 'eric')).all()
11 ret = session.query(Users).filter(
12 or_(
13 Users.id < 2,
14 and_(Users.name == 'eric', Users.id > 3),
15 Users.extra != ""
16 )).all()
17
18
19 # 通配符
20 ret = session.query(Users).filter(Users.name.like('e%')).all()
21 ret = session.query(Users).filter(~Users.name.like('e%')).all()
22
23 # 限制
24 ret = session.query(Users)[1:2]
25
26 # 排序
27 ret = session.query(Users).order_by(Users.name.desc()).all()
28 ret = session.query(Users).order_by(Users.name.desc(), Users.id.asc()).all()
29
30 # 分组
31 from sqlalchemy.sql import func
32
33 ret = session.query(Users).group_by(Users.extra).all()
34 ret = session.query(
35 func.max(Users.id),
36 func.sum(Users.id),
37 func.min(Users.id)).group_by(Users.name).all()
38
39 ret = session.query(
40 func.max(Users.id),
41 func.sum(Users.id),
42 func.min(Users.id)).group_by(Users.name).having(func.min(Users.id) >2).all()
43
44 # 连表
45
46 ret = session.query(Users, Favor).filter(Users.id == Favor.nid).all()
47
48 ret = session.query(Person).join(Favor).all()
49
50 ret = session.query(Person).join(Favor, isouter=True).all()
51
52
53 # 组合
54 q1 = session.query(Users.name).filter(Users.id > 2)
55 q2 = session.query(Favor.caption).filter(Favor.nid < 2)
56 ret = q1.union(q2).all()
57
58 q1 = session.query(Users.name).filter(Users.id > 2)
59 q2 = session.query(Favor.caption).filter(Favor.nid < 2)
60 ret = q1.union_all(q2).all()
View Code
更多功能参见文档，猛击这里下载PDF
｡◕‿◕｡笔记详细整理：ORM框架创建表和操作表
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1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3
4 ########################### 对象关系映射（英语：(Object Relational Mapping，简称ORM #################################
5
6 from sqlalchemy.ext.declarative import declarative_base
7 from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index,CHAR,VARCHAR
8 from sqlalchemy.orm import sessionmaker, relationship
9 from sqlalchemy import create_engine
10
11 Base = declarative_base()
12
13 engine = create_engine("mysql+pymysql://root:@127.0.0.1:3306/s4day63?charset=utf8", max_overflow=5)
14
15 # 创建单表 (如下创建了两个类，也就是两个表；类下面的内容就是表里的列)
16 class UserType(Base):
17 __tablename__ = 'usertype' #这一行是表名
18 id = Column(Integer, primary_key=True, autoincrement=True) #Colunm 列
19 title = Column(VARCHAR(32), nullable=True, index=True)
20
21 class Users(Base):
22 __tablename__ = 'users' #这一行是表名
23 id = Column(Integer, primary_key=True, autoincrement=True)
24 name = Column(VARCHAR(32), nullable=True, index=True)
25 email = Column(VARCHAR(16), unique=True)
26 user_type_id = Column(Integer,ForeignKey("usertype.id"))
27
28
29 # 联合唯一索引
30 # __table_args__ = (
31 # UniqueConstraint('id', 'name', name='uix_id_name'),
32 # Index('ix_n_ex','name', 'email',),
33 # )
34
35
36 def create_db():
37 Base.metadata.create_all(engine) #创建表
38
39 def drop_db():
40 Base.metadata.drop_all(engine) #删除表
41
42 # create_db() #调用创建表函数
43 # drop_db() #调用删除表函数
44
45
46 Session = sessionmaker(bind=engine)
47 session = Session()
48
49
50 # 类 -> 代指的就是表
51 # 对象 -> 代指的就是行
52
53
54 # ###### 增 ######
55 # obj1 = UserType(title='普通用户') #向UserType表中插入1条数据
56 # session.add(obj1)
57 #
58 # objs =[ #向UserType表中插入多条数据
59 # UserType(title='超级用户'),
60 # UserType(title='白金用户'),
61 # UserType(title='黑金用户'),
62 # ]
63 # session.add_all(objs)
64
65 # obj2 = Users(name='青铜') #向Users表中插入1条数据
66 # session.add(obj2)
67 #
68 # objs2 = [ #向Users表中插入多条数据
69 # Users(name='白银'),
70 # Users(name='黄金'),
71 # Users(name='铂金'),
72 # Users(name='钻石'),
73 # Users(name='大师'),
74 # Users(name='王者'),
75 # ]
76 # session.add_all(objs2)
77
78
79 # ###### 查 ######
80 # print(session.query(UserType)) #查看表UserType，这里打印出来的是SQL语句
81 # user_type_list = session.query(UserType).all() #查看表UserType所有内容
82 # for row in user_type_list: #遍历表UserType所有内容
83 # print(row.id,row.title) #打印遍历结果中的id和title
84
85
86 # #过滤查询，相当于where，设定查询条件,filter(过滤),这里意思是查询UserType里面的id和title,并且过滤条件为id>2的
87 # user_type_list = session.query(UserType.id,UserType.title).filter(UserType.id > 2)
88 # for row in user_type_list:
89 # print(row.id,row.title)
90
91
92 # ###### 删除 ######
93 # session.query(UserType.id,UserType.title).filter(UserType.id > 2).delete()
94
95
96 # ###### 修改 ######
97 #**********批量修改----这里批量修改title为黑金
98 # session.query(UserType.id,UserType.title).filter(UserType.id > 0).update({"title" : "黑金"})
99
100 #**********批量字符串类型修改----这里是批量在原title基础上+'aaa',加上的内容是字符串类型,修改对象也应是字符串类型
101 # session.query(UserType.id,UserType.title).filter(UserType.id > 0).update({UserType.title: UserType.title + "aaa"}, synchronize_session=False)
102
103 #**********批量数字类型修改----这里是批量在原num基础上+'111',加上的内容是数字类型，修改对象也应是数字类型
104 # session.query(UserType.id,UserType.title).filter(UserType.id > 0).update({"num": Users.num + 111}, synchronize_session="evaluate")
105
106
107 session.commit() #执行完提交
108 session.close() #关闭这次会话
ORM框架创建表和操作表
