pymysql
pymsql是Python中操作MySQL的模块,其使用方法和MySQLdb几乎相同
一、下载安装
pip3 install pymysql
二、操作使用
1、执行SQL
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()
2、获取新创建数据自增ID
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
3、获取查询数据
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()
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:
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()
SQLAlchemy
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:
pip3 install SQLAlchemy
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:
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。
#!/usr/bin/env python
# -*- coding:utf-8 -*-
from sqlalchemy import create_engine
engine = create_engine("mysql+pymysql://root:123@127.0.0.1:3306/t1", max_overflow=5)
# 执行SQL
# cur = engine.execute(
# "INSERT INTO hosts (host, color_id) VALUES ('1.1.1.22', 3)"
# )
# 新插入行自增ID
# cur.lastrowid
# 执行SQL
# cur = engine.execute(
# "INSERT INTO hosts (host, color_id) VALUES(%s, %s)",[('1.1.1.22', 3),('1.1.1.221', 3),]
# )
# 执行SQL
# cur = engine.execute(
# "INSERT INTO hosts (host, color_id) VALUES (%(host)s, %(color_id)s)",
# host='1.1.1.99', color_id=3
# )
# 执行SQL
# cur = engine.execute('select * from hosts')
# 获取第一行数据
# cur.fetchone()
# 获取第n行数据
# cur.fetchmany(3)
# 获取所有数据
# cur.fetchall()
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
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)
67 注:设置外检的另一种方式 ForeignKeyConstraint(['other_id'], ['othertable.other_id'])
2、操作表
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()
表结构加数据库连接
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()
增
1 session.query(Users).filter(Users.id > 2).delete()
2 session.commit()
删
1 session.query(Users).filter(Users.id > 2).update({"name" : "099"})
2 session.query(Users).filter(Users.id > 2).update({Users.name: Users.name + "099"}, synchronize_session=False)
3 session.query(Users).filter(Users.id > 2).update({"num": Users.num + 1}, synchronize_session="evaluate")
4 session.commit()
改
1 ret = session.query(Users).all()
2 ret = session.query(Users.name, Users.extra).all()
3 ret = session.query(Users).filter_by(name='alex').all()
4 ret = session.query(Users).filter_by(name='alex').first()
查
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()
其他