简介
MySQL 是目前使用最广泛的数据库之一，它有着良好的性能，能够跨平台，支持分布式，能够承受高并发。如果还没有安装 MySQL，下载地址：https://dev.mysql.com/downloads/mysql/5.7.html，安装参考：https://jingyan.baidu.com/article/fc07f989b298ca12ffe519b6.html。
Python 大致有如下 5 种方式操作 MySQL。
- MySQL-python
MySQL-python 也称 MySQLdb，基于 C 库开发，曾经是一个十分流行的 MySQL 驱动，具有出色的性能，但其早已停更，仅支持 Python2，不支持 Python3，现在基本不推荐使用了，取而代之的是它的衍生版。
- mysqlclient
MySQLdb 的 Fork 版本，完全兼容 MySQLdb，支持 Python3，它是 Django ORM 的依赖工具，如果你喜欢用原生 SQL 操作数据库，那么推荐使用它。
- PyMySQL
PyMySQL 采用纯 Python 开发，兼容 MySQLdb，性能不如 MySQLdb，安装方便，支持 Python3。
- peewee
peewee 是一个流行的 ORM 框架，实现了对象与数据库表的映射，兼容多种数据库，我们无需知道原生 SQL，只要了解面向对象的思想就可以简单、快速的操作相应数据库，支持 Python3。
- SQLAlchemy
SQLAlchemy 是一个 ORM 框架，同时也支持原生 SQL，支持 Python3，它类似于 Java 的 Hibernate 框架。
实际操作
因为 MySQLdb 不支持 Python3，这里我们只介绍其中后 4 中方式的使用，先使用如下建表语句创建一张简单的数据库表。
CREATE TABLE student ( id int(10) AUTO_INCREMENT PRIMARY KEY, name varchar(255) NOT NULL, age int(10) NOT NULL );
mysqlclient
执行 pip install mysqlclient 进行安装，看一下具体操作。
新增
import MySQLdb connect = MySQLdb.connect( # 主机 host='localhost', # 端口号 port=3306, # 用户名 user='root', # 密码 passwd='root', # 数据库名称 db='test', # 指定字符的编、解码格式 use_unicode=True, charset='utf8') # 先获取游标，再进行相应 SQL 操作 cursor = connect .cursor() # 执行新增 SQL sql = 'insert into student (name, age) values(%s,%s);' data = [ ('张三', '22'), ('李四', '23') ] cursor.executemany(sql, data) # 提交 connect.commit() # 关闭 cursor.close() connect.close()
查询
import MySQLdb connect = MySQLdb.connect( host='localhost', port=3306, user='root', passwd='root', db='test', use_unicode=True, charset='utf8') cursor = connect.cursor() cursor.execute('SELECT * FROM student') print(cursor.fetchall()) cursor.close() connect.close()
cursor 查看方法
- fetchone() 获取结果集的下一行
- fetchmany(size) 获取结果集的下几行务
- fetchall() 获取结果集中剩下的所有行
修改
import MySQLdb connect = MySQLdb.connect( host='localhost', port=3306, user='root', passwd='root', db='test', use_unicode=True, charset='utf8') cursor = connect.cursor() cursor.execute("UPDATE student SET name='张四' WHERE id = 1") connect.commit() cursor.close() connect.close()
删除
import MySQLdb connect = MySQLdb.connect( host='localhost', port=3306, user='root', passwd='root', db='test', use_unicode=True, charset='utf8') cursor = connect.cursor() cursor.execute("DELETE FROM student WHERE id = 1") connect.commit() cursor.close() connect.close()
PyMySQL
执行 pip install pymysql 进行安装，使用方式与 mysqlclient 基本类似。
import pymysql connect = pymysql.connect( host='localhost', port=3306, user='root', password='root', database='test', charset='utf8' ) cursor = connect.cursor() sql = 'insert into student (name, age) values(%s,%s);' data = [ ('张三', '22'), ('李四', '23') ] cursor.executemany(sql, data) connect.commit() cursor.execute('SELECT * FROM student') print(cursor.fetchall()) cursor.close() connect.close()
peewee
执行 pip install peewee 进行安装，看一下具体操作。
定义映射类
from peewee import * # 连接数据库 db = MySQLDatabase('test', host='localhost', port=3306, user='root', passwd='root', charset='utf8') # 映射类 class Teacher(Model): id = AutoField(primary_key=True) name = CharField() age = IntegerField() class Meta: database = db # 创建表 db.create_tables([Teacher])
新增
from peewee import * db = MySQLDatabase('test', host='localhost', port=3306, user='root', passwd='root', charset='utf8') class Teacher(Model): id = AutoField(primary_key=True) name = CharField() age = IntegerField() class Meta: database = db t1 = Teacher(name='张三', age=22) t2 = Teacher(name='李四', age=33) t3 = Teacher(name='王五', age=33) t1.save() t2.save() t3.save()
查询
from peewee import * db = MySQLDatabase('test', host='localhost', port=3306, user='root', passwd='root', charset='utf8') class Teacher(Model): id = AutoField(primary_key=True) name = CharField() age = IntegerField() class Meta: database = db # 查询单条数据 t = Teacher.get(Teacher.id == 1) print('name：', t.name) # 查询多条 ts = Teacher.select().where(Teacher.age == 33) for t in ts: print('name：', t.name)
修改
from peewee import * db = MySQLDatabase('test', host='localhost', port=3306, user='root', passwd='root', charset='utf8') class Teacher(Model): id = AutoField(primary_key=True) name = CharField() age = IntegerField() class Meta: database = db t = Teacher.update({Teacher.name: '张四'}).where(Teacher.id == 1) t.execute()
删除
from peewee import * db = MySQLDatabase('test', host='localhost', port=3306, user='root', passwd='root', charset='utf8') class Teacher(Model): id = AutoField(primary_key=True) name = CharField() age = IntegerField() class Meta: database = db Teacher.delete().where(Teacher.id == 2).execute()
SQLAlchemy
执行 pip install sqlalchemy 进行安装，看一下具体操作。
定义映射类
from sqlalchemy import create_engine from sqlalchemy.ext.declarative import declarative_base from sqlalchemy import Column, Integer, String engine = create_engine('mysql+mysqldb://root:root@localhost:3306/test?charset=utf8', # 打印执行语句 echo=True, # 连接池大小 pool_size=10, # 指定时间内回收连接 pool_recycle=3600) # 映射基类 Base = declarative_base() # 具体映射类 class Teacher(Base): # 指定映射表名 __tablename__ = 'teacher' # 映射字段 id = Column(Integer, primary_key=True) name = Column(String(30)) age = Column(Integer) # 创建表 Base.metadata.create_all(engine)
新增
from sqlalchemy import create_engine from sqlalchemy.ext.declarative import declarative_base from sqlalchemy import Column, Integer, String from sqlalchemy.orm import sessionmaker engine = create_engine('mysql+mysqldb://root:root@localhost:3306/test?charset=utf8', # 打印执行语句 echo=True, # 连接池大小 pool_size=10, # 指定时间内回收连接 pool_recycle=3600) # 映射基类 Base = declarative_base() # 具体映射类 class Teacher(Base): # 指定映射表名 __tablename__ = 'teacher' # 映射字段 id = Column(Integer, primary_key=True) name = Column(String(30)) age = Column(Integer) Session = sessionmaker(bind=engine) # 创建 Session 类实例 session = Session() ls = [] t1 = Teacher(name='张三', age=22) t2 = Teacher(name='李四', age=33) t3 = Teacher(name='王五', age=33) ls.append(t1) ls.append(t2) ls.append(t3) session.add_all(ls) session.commit() session.close()
查询
from sqlalchemy import create_engine from sqlalchemy.ext.declarative import declarative_base from sqlalchemy import Column, Integer, String from sqlalchemy.orm import sessionmaker engine = create_engine('mysql+mysqldb://root:root@localhost:3306/test?charset=utf8', # 打印执行语句 echo=True, # 连接池大小 pool_size=10, # 指定时间内回收连接 pool_recycle=3600) # 映射基类 Base = declarative_base() # 具体映射类 class Teacher(Base): # 指定映射表名 __tablename__ = 'teacher' # 映射字段 id = Column(Integer, primary_key=True) name = Column(String(30)) age = Column(Integer) Session = sessionmaker(bind=engine) # 创建 Session 类实例 session = Session() # 查询一条数据，filter 相当于 where 条件 t = session.query(Teacher).filter(Teacher.id==1).one() print('---', t.name) # 查询所有数据 ts = session.query(Teacher).filter(Teacher.age==33).all() for t in ts: print('===', t.name)
修改
from sqlalchemy import create_engine from sqlalchemy.ext.declarative import declarative_base from sqlalchemy import Column, Integer, String from sqlalchemy.orm import sessionmaker engine = create_engine('mysql+mysqldb://root:root@localhost:3306/test?charset=utf8', # 打印执行语句 echo=True, # 连接池大小 pool_size=10, # 指定时间内回收连接 pool_recycle=3600) # 映射基类 Base = declarative_base() # 具体映射类 class Teacher(Base): # 指定映射表名 __tablename__ = 'teacher' # 映射字段 id = Column(Integer, primary_key=True) name = Column(String(30)) age = Column(Integer) Session = sessionmaker(bind=engine) # 创建 Session 类实例 session = Session() t = session.query(Teacher).filter(Teacher.id==1).one() print('修改前名字-->', t.name) t.name = '张四' session.commit() print('修改后名字-->', t.name)
删除
from sqlalchemy import create_engine from sqlalchemy.ext.declarative import declarative_base from sqlalchemy import Column, Integer, String from sqlalchemy.orm import sessionmaker engine = create_engine('mysql+mysqldb://root:root@localhost:3306/test?charset=utf8', # 打印执行语句 echo=True, # 连接池大小 pool_size=10, # 指定时间内回收连接 pool_recycle=3600) # 映射基类 Base = declarative_base() # 具体映射类 class Teacher(Base): # 指定映射表名 __tablename__ = 'teacher' # 映射字段 id = Column(Integer, primary_key=True) name = Column(String(30)) age = Column(Integer) Session = sessionmaker(bind=engine) # 创建 Session 类实例 session = Session() t = session.query(Teacher).filter(Teacher.id==1).one() session.delete(t) session.commit()
