Python筑基之旅-MySQL数据库(四)

目录

一、数据表操作

1、新增记录

1-1、用mysql-connector-python库

1-2、用PyMySQL库

1-3、用PeeWee库

1-4、用SQLAlchemy库

2、删除记录

2-1、用mysql-connector-python库

2-2、用PyMySQL库

2-3、用PeeWee库

2-4、用SQLAlchemy库

3、修改记录

3-1、用mysql-connector-python库

3-2、用PyMySQL库

3-3、用PeeWee库

3-4、用SQLAlchemy库

4、查询记录

4-1、用mysql-connector-python库

4-2、用PyMySQL库

4-3、用PeeWee库

4-4、用SQLAlchemy库

二、推荐阅读

1、Python函数之旅

2、Python算法之旅

3、博客个人主页

一、数据表操作

        在MySQL服务器上已有数据库test_database，且该数据库下已有数据表myelsa_table，此数据表包含4个字段：name，ID_Card，age，city，现借助第三方库对该数据表进行增、删、改、查等操作。

1、新增记录

1-1、用mysql-connector-python库

import mysql.connector
# 数据库连接配置
config = {'username': 'root',  # 替换为你的MySQL用户名'password': '123456',  # 替换为你的MySQL密码'host': '127.0.0.1',  # 如果数据库在远程服务器上，请替换为相应的主机名或IP地址'database': 'test_database',  # 数据库名
}
# 定义要插入的数据
new_record = {'name': 'Myelsa','ID_Card': '443689564710526448','age': 18,'city': 'Guangzhou'
}
# SQL插入语句
insert_query = """  
INSERT INTO myelsa_table (name, ID_Card, age, city)  
VALUES (%s, %s, %s, %s)  
"""
try:# 连接到数据库cnx = mysql.connector.connect(**config)cursor = cnx.cursor()# 执行SQL插入语句cursor.execute(insert_query, (new_record['name'], new_record['ID_Card'], new_record['age'], new_record['city']))# 提交更改cnx.commit()print("Record inserted successfully!")
except mysql.connector.Error as err:print(f"Error: '{err}'")
finally:# 关闭游标和连接if cursor:cursor.close()if cnx.is_connected():cnx.close()

1-2、用PyMySQL库

import pymysql
# 数据库连接配置
config = {'user': 'root',  # 替换为你的MySQL用户名'password': '123456',  # 替换为你的MySQL密码'host': '127.0.0.1',  # 如果数据库在远程服务器上，请替换为相应的主机名或IP地址'database': 'test_database',  # 数据库名'charset': 'utf8mb4',  # 添加字符集配置，防止编码问题'cursorclass': pymysql.cursors.DictCursor  # 使用字典游标以便轻松访问列名
}
# 定义要插入的数据
new_record = {'name': 'Myelsa','ID_Card': '443689564710526448','age': 18,'city': 'Guangzhou'
}
# SQL插入语句
insert_query = """  
INSERT INTO myelsa_table (name, ID_Card, age, city)  
VALUES (%s, %s, %s, %s)  
"""
try:# 连接到数据库cnx = pymysql.connect(**config)with cnx.cursor() as cursor:# 使用with语句确保游标在使用完毕后被关闭# 执行SQL插入语句cursor.execute(insert_query, (new_record['name'], new_record['ID_Card'], new_record['age'], new_record['city']))# 提交更改cnx.commit()print("Record inserted successfully!")
except pymysql.Error as err:print(f"Error: '{err}'")
# 使用with语句连接数据库时，在with块结束后连接将自动关闭
# 如果没有使用with语句，需要显式关闭连接
if cnx.open:cnx.close()

1-3、用PeeWee库

from peewee import *
# 数据库连接配置
db = MySQLDatabase('test_database', user='root', password='123456', host='127.0.0.1')
# 定义模型
class MyelsaTable(Model):name = CharField()ID_Card = CharField()age = IntegerField()city = CharField()class Meta:database = dbtable_name = 'myelsa_table'
# 连接到数据库
db.connect()
# 创建表（如果尚不存在）
db.create_tables([MyelsaTable])
# 插入数据
new_record = {'name': 'Myelsa','ID_Card': '443689564710526448','age': 18,'city': 'Guangzhou'
}
try:MyelsaTable.create(name=new_record['name'],ID_Card=new_record['ID_Card'],age=new_record['age'],city=new_record['city'])print("Record inserted successfully!")
except IntegrityError as e:print(f"Error: '{e}'")
finally:# 关闭数据库连接db.close()

1-4、用SQLAlchemy库

from sqlalchemy import create_engine, Column, Integer, String
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
from sqlalchemy.exc import SQLAlchemyError
# 定义基类
Base = declarative_base()
# 定义数据库模型类
class MyElsaTable(Base):__tablename__ = 'myelsa_table'ID_Card = Column(String, primary_key=True)name = Column(String)age = Column(Integer)city = Column(String)def __repr__(self):return f"<MyElsaTable(ID_Card={self.ID_Card}, name={self.name}, age={self.age}, city={self.city})>"
# 数据库连接配置
config = {'username': 'root',  # 替换为你的MySQL用户名'password': '123456',  # 替换为你的MySQL密码'host': '127.0.0.1',  # 如果数据库在远程服务器上，请替换为相应的主机名或IP地址'database': 'test_database',  # 数据库名
}
# 创建数据库引擎
engine = create_engine(f'mysql+pymysql://{config["username"]}:{config["password"]}@{config["host"]}/{config["database"]}')
# 确保所有表都已创建（可选）
Base.metadata.create_all(engine)
# 创建会话类
Session = sessionmaker(bind=engine)
# 定义要插入的数据
new_record = {'name': 'Myelsa','ID_Card': '443689564710526448','age': 18,'city': 'Guangzhou'
}
try:# 使用上下文管理器自动管理会话with Session() as session:# 创建新的模型实例new_entry = MyElsaTable(**new_record)# 将新实例添加到会话中session.add(new_entry)# 提交更改session.commit()print("Record inserted successfully!")
except SQLAlchemyError as e:print(f"Error: '{e}'")# 在使用上下文管理器时，无需显式回滚，因为上下文管理器会在退出时处理它

2、删除记录

2-1、用mysql-connector-python库

import mysql.connector
# 数据库连接配置
config = {'username': 'root',  # 替换为你的MySQL用户名'password': '123456',  # 替换为你的MySQL密码'host': '127.0.0.1',  # 如果数据库在远程服务器上，请替换为相应的主机名或IP地址'database': 'test_database',  # 数据库名
}
# 要删除的记录的ID_Card值
id_card_to_delete = '443689564710526448'
# SQL删除语句
delete_query = """  
DELETE FROM myelsa_table  
WHERE ID_Card = %s  
"""
try:# 连接到数据库cnx = mysql.connector.connect(**config)cursor = cnx.cursor()# 执行SQL删除语句cursor.execute(delete_query, (id_card_to_delete,))# 提交更改cnx.commit()print(f"Record with ID_Card '{id_card_to_delete}' deleted successfully!")
except mysql.connector.Error as err:print(f"Error: '{err}'")
finally:# 关闭游标和连接if cursor:cursor.close()if cnx.is_connected():cnx.close()

2-2、用PyMySQL库

import pymysql
# 数据库连接配置
config = {'user': 'root',  # 替换为你的MySQL用户名'password': '123456',  # 替换为你的MySQL密码'host': '127.0.0.1',  # 如果数据库在远程服务器上，请替换为相应的主机名或IP地址'database': 'test_database',  # 数据库名'charset': 'utf8mb4',  # 添加字符集配置，防止编码问题'cursorclass': pymysql.cursors.DictCursor  # 使用字典游标（虽然在这个删除操作中不是必需的）
}
# 要删除的记录的ID_Card值
id_card_to_delete = '443689564710526448'
# SQL删除语句
delete_query = """    
DELETE FROM myelsa_table    
WHERE ID_Card = %s    
"""
try:# 连接到数据库cnx = pymysql.connect(**config)with cnx.cursor() as cursor:# 使用with语句确保游标在使用完毕后被关闭# 执行SQL删除语句cursor.execute(delete_query, (id_card_to_delete,))# 提交更改cnx.commit()print(f"Record with ID_Card '{id_card_to_delete}' deleted successfully!")
except pymysql.Error as err:print(f"Error: '{err}'")
# 使用with语句连接数据库时，在with块结束后连接将自动关闭
# 如果没有使用with语句，需要显式关闭连接
if cnx.open:cnx.close()

2-3、用PeeWee库

from peewee import *
# 数据库连接配置
db = MySQLDatabase('test_database', user='root', password='123456', host='127.0.0.1')
# 定义模型，映射到myelsa_table表
class Myelsa_Table(Model):name = CharField()ID_Card = CharField(unique=True)  # 假设ID_Card是唯一的age = IntegerField()city = CharField()class Meta:database = db
# 连接到数据库
db.connect()
# 要删除的记录的ID_Card值
id_card_to_delete = '443689564710526448'
try:# 使用模型来删除记录query = Myelsa_Table.delete().where(Myelsa_Table.ID_Card == id_card_to_delete)query.execute()print(f"Record with ID_Card '{id_card_to_delete}' deleted successfully!")
except Exception as e:print(f"Error: '{e}'")
finally:# 关闭数据库连接（Peewee会在连接池中管理连接，通常不需要显式关闭）# 但如果你确定不再需要连接，可以调用db.close()# db.close()pass
# 注意：在实际应用中，通常不需要显式关闭连接，因为Peewee会管理连接池
# 但在某些情况下，例如脚本结束时，你可能想要确保所有资源都被释放

2-4、用SQLAlchemy库

from sqlalchemy import create_engine, Column, Integer, String, MetaData, Table
from sqlalchemy.orm import sessionmaker
from sqlalchemy.exc import SQLAlchemyError
# 数据库连接配置
config = {'username': 'root',  # 替换为你的MySQL用户名'password': '123456',  # 替换为你的MySQL密码'host': '127.0.0.1',  # 如果数据库在远程服务器上，请替换为相应的主机名或IP地址'database': 'test_database',  # 数据库名'port': 3306,  # 如果端口不是默认的3306，请添加此行并替换为正确的端口
}
# 创建数据库引擎
engine = create_engine(f'mysql+pymysql://{config["username"]}:{config["password"]}@{config["host"]}:{config["port"]}/{config["database"]}')
# 要删除的记录的ID_Card值
id_card_to_delete = '443689564710526448'
# 定义元数据（如果使用ORM，则无需此步骤，但这里为简单起见使用Table对象）
metadata = MetaData()
myelsa_table = Table('myelsa_table', metadata, autoload_with=engine)
# 创建会话类
Session = sessionmaker(bind=engine)
try:# 创建会话对象session = Session()# 执行SQL删除语句（这里使用session.execute而不是ORM方法）session.execute(myelsa_table.delete().where(myelsa_table.c.ID_Card == id_card_to_delete))# 提交更改session.commit()print(f"Record with ID_Card '{id_card_to_delete}' deleted successfully!")
except SQLAlchemyError as e:print(f"Error: '{e}'")# 如果出错，回滚更改session.rollback()
finally:# 关闭会话session.close()

3、修改记录

3-1、用mysql-connector-python库

import mysql.connector
# 数据库连接配置
config = {'username': 'root',  # 替换为你的MySQL用户名'password': '123456',  # 替换为你的MySQL密码'host': '127.0.0.1',  # 如果数据库在远程服务器上，请替换为相应的主机名或IP地址'database': 'test_database',  # 数据库名
}
# 要更新的记录的ID_Card值
id_card_to_update = '443689564710526448'
# 新的记录值
new_values = {'name': 'Jimmy','age': 15,'city': 'Foshan'
}
# SQL更新语句
update_query = """  
UPDATE myelsa_table  
SET name = %s, age = %s, city = %s  
WHERE ID_Card = %s  
"""
try:# 连接到数据库cnx = mysql.connector.connect(**config)cursor = cnx.cursor()# 执行SQL更新语句cursor.execute(update_query, (new_values['name'], new_values['age'], new_values['city'], id_card_to_update))# 提交更改cnx.commit()print(f"Record with ID_Card '{id_card_to_update}' updated successfully!")
except mysql.connector.Error as err:print(f"Error: '{err}'")
finally:# 关闭游标和连接if cursor:cursor.close()if cnx.is_connected():cnx.close()

3-2、用PyMySQL库

import pymysql
# 数据库连接配置
config = {'user': 'root',  # 替换为你的MySQL用户名'password': '123456',  # 替换为你的MySQL密码'host': '127.0.0.1',  # 如果数据库在远程服务器上，请替换为相应的主机名或IP地址'database': 'test_database',  # 数据库名'charset': 'utf8mb4',  # 添加字符集配置，防止编码问题'cursorclass': pymysql.cursors.DictCursor  # 虽然在更新操作中不是必需的，但这里保持一致
}
# 要更新的记录的ID_Card值
id_card_to_update = '443689564710526448'
# 新的记录值
new_values = {'name': 'Jimmy','age': 15,'city': 'Foshan'
}
# SQL更新语句
update_query = """    
UPDATE myelsa_table    
SET name = %s, age = %s, city = %s    
WHERE ID_Card = %s    
"""
try:# 连接到数据库cnx = pymysql.connect(**config)with cnx.cursor() as cursor:# 使用with语句确保游标在使用完毕后被关闭# 执行SQL更新语句cursor.execute(update_query, (new_values['name'], new_values['age'], new_values['city'], id_card_to_update))# 提交更改cnx.commit()print(f"Record with ID_Card '{id_card_to_update}' updated successfully!")
except pymysql.MySQLError as err:print(f"Error: '{err}'")
finally:
# 使用with语句时，连接会在with块结束时自动关闭
# 如果连接没有通过with管理，需要在这里关闭if cnx.open:cnx.close()

3-3、用PeeWee库

from peewee import *
# 定义数据库连接
db = MySQLDatabase('test_database', user='root', password='123456', host='127.0.0.1')
# 定义数据库模型类
class MyElsa_Table(Model):ID_Card = CharField(primary_key=True)  # 注意：这里保留了你的原始字段命名name = CharField()age = IntegerField()city = CharField()class Meta:database = db
# 连接到数据库
db.connect()
# 要更新的记录的ID_Card值
id_card_to_update = '443689564710526448'
# 新的记录值
new_values = {'name': 'Jimmy','age': 15,'city': 'Foshan'
}
try:# 使用ORM方法执行更新操作query = (MyElsa_Table.update(name=new_values['name'], age=new_values['age'], city=new_values['city']).where(MyElsa_Table.ID_Card == id_card_to_update))query.execute()# 如果没有错误，打印成功消息print(f"Record with ID_Card '{id_card_to_update}' updated successfully!")
except Exception as e:# 捕获异常并打印错误信息print(f"Error: '{e}'")
finally:# 关闭数据库连接db.close()

3-4、用SQLAlchemy库

from sqlalchemy import create_engine, MetaData, Table, Column, Integer, String
from sqlalchemy.orm import sessionmaker
from sqlalchemy.exc import SQLAlchemyError
# 数据库连接配置
config = {'username': 'root',  # 替换为你的MySQL用户名'password': '123456',  # 替换为你的MySQL密码'host': '127.0.0.1',  # 如果数据库在远程服务器上，请替换为相应的主机名或IP地址'database': 'test_database',  # 数据库名'port': 3306,  # 如果端口不是默认的3306，请添加此行并替换为正确的端口'echo': False  # 如果想看到执行的SQL语句，设置为True
}
# 创建数据库引擎
engine = create_engine(f'mysql+pymysql://{config["username"]}:{config["password"]}@{config["host"]}:{config["port"]}/{config["database"]}',echo=config['echo'])
# 定义元数据
metadata = MetaData()
# 假设你的表结构如下（需要根据实际情况调整列类型和名称）
myelsa_table = Table('myelsa_table', metadata,Column('ID_Card', String, primary_key=True),Column('name', String),Column('age', Integer),Column('city', String),autoload_with=engine)
# 要更新的记录的ID_Card值
id_card_to_update = '443689564710526448'
# 新的记录值
new_values = {'name': 'Jimmy','age': 15,'city': 'Foshan'
}
# 创建会话类
Session = sessionmaker(bind=engine)
try:# 创建会话对象session = Session()# 构造更新语句stmt = myelsa_table.update().where(myelsa_table.c.ID_Card == id_card_to_update).values(**new_values)# 执行更新session.execute(stmt)# 提交更改session.commit()print(f"Record with ID_Card '{id_card_to_update}' updated successfully!")
except SQLAlchemyError as e:print(f"Error: '{e}'")# 如果出错，回滚更改session.rollback()
finally:# 关闭会话session.close()

4、查询记录

4-1、用mysql-connector-python库

import mysql.connector
# 数据库连接配置
config = {'username': 'root',  # 替换为你的MySQL用户名'password': '123456',  # 替换为你的MySQL密码'host': '127.0.0.1',  # 如果数据库在远程服务器上，请替换为相应的主机名或IP地址'database': 'test_database',  # 数据库名
}
# 查询所有记录的SQL语句
query_all = """  
SELECT * FROM myelsa_table  
"""
# 查询特定记录的SQL语句（例如，根据ID_Card查询）
id_card_to_query = '443689564710526448'
query_by_id_card = """  
SELECT * FROM myelsa_table WHERE ID_Card = %s  
"""
try:# 连接到数据库cnx = mysql.connector.connect(**config)cursor = cnx.cursor()# 执行查询所有记录的SQL语句cursor.execute(query_all)# 获取所有记录for (name, id_card, age, city) in cursor:print(f"Name: {name}, ID Card: {id_card}, Age: {age}, City: {city}")# 如果需要查询特定记录，取消注释以下代码# cursor.execute(query_by_id_card, (id_card_to_query,))# record = cursor.fetchone()# if record:#     (name, id_card, age, city) = record#     print(f"Name: {name}, ID Card: {id_card}, Age: {age}, City: {city}")# else:#     print(f"No record found for ID Card: {id_card_to_query}")
except mysql.connector.Error as err:print(f"Error: '{err}'")
finally:# 关闭游标和连接if cursor:cursor.close()if cnx.is_connected():cnx.close()

4-2、用PyMySQL库

import pymysql
# 数据库连接配置
config = {'user': 'root',  # 替换为你的MySQL用户名'password': '123456',  # 替换为你的MySQL密码'host': '127.0.0.1',  # 如果数据库在远程服务器上，请替换为相应的主机名或IP地址'database': 'test_database',  # 数据库名'charset': 'utf8mb4',  # 添加字符集配置，防止编码问题'cursorclass': pymysql.cursors.DictCursor  # 使用字典游标以便按列名访问数据
}
# 查询所有记录的SQL语句
query_all = """    
SELECT * FROM myelsa_table    
"""
# 查询特定记录的SQL语句（例如，根据ID_Card查询）
id_card_to_query = '443689564710526448'
query_by_id_card = """    
SELECT * FROM myelsa_table WHERE ID_Card = %s    
"""
try:# 连接到数据库cnx = pymysql.connect(**config)with cnx.cursor(pymysql.cursors.DictCursor) as cursor:  # 使用with语句自动管理游标# 执行查询所有记录的SQL语句cursor.execute(query_all)# 获取所有记录for row in cursor:print(f"Name: {row['name']}, ID Card: {row['ID_Card']}, Age: {row['age']}, City: {row['city']}")# 如果需要查询特定记录，取消注释以下代码# cursor.execute(query_by_id_card, (id_card_to_query,))# record = cursor.fetchone()# if record:#     print(f"Name: {record['name']}, ID Card: {record['ID_Card']}, Age: {record['age']}, City: {record['city']}")# else:#     print(f"No record found for ID Card: {id_card_to_query}")# 注意：因为使用了with语句，所以不需要显式关闭游标# 提交（在这里其实不需要，因为只是查询）cnx.commit()except pymysql.MySQLError as err:print(f"Error: '{err}'")
finally:
# 使用with语句时，连接会在with块结束时自动关闭
# 如果连接没有通过with管理，需要在这里关闭if cnx.open:cnx.close()

4-3、用PeeWee库

from peewee import *
# 数据库连接配置
db = MySQLDatabase('test_database', user='root', password='123456', host='127.0.0.1')
# 定义数据库模型类
class MyElsa_Table(Model):ID_Card = CharField(primary_key=True)name = CharField()age = IntegerField()city = CharField()class Meta:database = db
# 连接到数据库
db.connect()
# 查询所有记录
def query_all_records():for record in MyElsa_Table.select():print(f"Name: {record.name}, ID Card: {record.ID_Card}, Age: {record.age}, City: {record.city}")
# 查询特定记录（根据ID_Card）
def query_record_by_id_card(id_card):record = MyElsa_Table.get_or_none(MyElsa_Table.ID_Card == id_card)if record:print(f"Name: {record.name}, ID Card: {record.ID_Card}, Age: {record.age}, City: {record.city}")else:print(f"No record found for ID Card: {id_card}")
# ID_Card要查询的特定值
id_card_to_query = '443689564710526448'
try:# 查询所有记录query_all_records()print("\n---\n")# 查询特定记录query_record_by_id_card(id_card_to_query)
except MyElsa_Table.DoesNotExist:print(f"No record found for ID Card: {id_card_to_query}")
except Exception as e:print(f"Error: '{e}'")
finally:# 关闭数据库连接（如果使用了连接池，则可能不需要显式关闭）db.close()

4-4、用SQLAlchemy库

from sqlalchemy import create_engine, Column, Integer, String, MetaData
from sqlalchemy.orm import sessionmaker
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.exc import SQLAlchemyError
# 声明基础类
Base = declarative_base()
# 定义ORM模型
class MyElsaTable(Base):__tablename__ = 'myelsa_table'id_card = Column(String, primary_key=True)name = Column(String)age = Column(Integer)city = Column(String)
# 数据库连接配置
config = {'username': 'root',  # 替换为你的MySQL用户名'password': '123456',  # 替换为你的MySQL密码'host': '127.0.0.1',  # 如果数据库在远程服务器上，请替换为相应的主机名或IP地址'database': 'test_database',  # 数据库名'port': 3306,  # 端口号，默认为3306'echo': False  # 是否打印SQL语句
}
# 创建数据库引擎
engine = create_engine(f'mysql+pymysql://{config["username"]}:{config["password"]}@{config["host"]}:{config["port"]}/{config["database"]}',echo=config['echo'])
# 创建Session类
Session = sessionmaker(bind=engine)
try:# 创建Session对象session = Session()# 查询所有记录all_records = session.query(MyElsaTable).all()for record in all_records:print(f"Name: {record.name}, ID Card: {record.id_card}, Age: {record.age}, City: {record.city}")# 查询特定记录（例如，根据ID_Card查询）id_card_to_query = '443689564710526448'record = session.query(MyElsaTable).filter_by(id_card=id_card_to_query).first()if record:print(f"Name: {record.name}, ID Card: {record.id_card}, Age: {record.age}, City: {record.city}")else:print(f"No record found for ID Card: {id_card_to_query}")
except SQLAlchemyError as e:print(f"Error: '{e}'")
finally:# 关闭Sessionsession.close()

二、推荐阅读

1、Python函数之旅

2、Python算法之旅

3、博客个人主页