数据库操作工具类（学生管理系统）

Mysql数据库工具类

新建MysqlHelper/DBUtils,实现操作数据库代码的 复用!

分析

数据库操作分为两类

非查询

 

# 增加,删,修改 都是非查询! 
# 实现方法: execute(sql语句,不同参数列表) 
# 增删改区别: sql语句不同, 参数个数不同!--->可以独一个共用方法,把sql和参数传过来! 
# 增删改功能都返回: 影响行数据! 
def my_execute(sql,params): 
,,,, 
    return num

 

查询

# 查询1条 游标.fetchone() 
# 查询多条 游标.fetchall()

连接数据库相关参考所有功能都需要--->放在类的初始化方法中init

获取数据库连接: 所有方法都需要!--->可以独立出来!

init方法,负责初始连接数据库需要各种参数!

 

class MysqlHelper():
    # 初始化方法
    def __init__(self,主机地址,端口,用户名,密码,字符集)
    self.主机地址=主机地址
    ....
    def my_execute(sql,prames):
        pass
    def connect():
        ......
# 使用
db = MysqlHelper(Ip地址,端口.用户名,密码.字符集)
# 增加
num =db.my_execute(sql语句,参数列表)
if num>0:
    print(\'成功\')
else:
    print(\'失败\')

 

代码实现

 

import  pymysql  # 导入数据库驱动模块!

class MysqlHelper():

    def __init__(self,host,port,user,passwd,db,charset=\'utf8\'):
        self.host= host
        self.port = port
        self.user = user
        self.passwd = passwd
        self.db = db
        self.charset=charset
        #self.conn = None

    def  connect(self):
        \'\'\'功能1: 获取连接\'\'\'
        self.conn = pymysql.connect(host=self.host,port=self.port,user=self.user,passwd=self.passwd,db=self.db,charset=self.charset)
        self.cursor =self.conn.cursor()

    def close(self):
        \'\'\'功能2:释放资源\'\'\'
        self.cursor.close() #关游标
        self.conn.close()# 关连接

    def my_execute(self,sql,params):
        \'\'\'
         增删改通用功能
        :param sql:  sql语句
        :param params: 参数列表
        :return: num 影响行数
        \'\'\'
        num =0
        # 1. 打开连接
        self.connect()
        num = self.cursor.execute(sql,params)
        self.conn.commit()
        self.close() #释放资源
        return num

    def get_one(self,sql,params):
        \'\'\'
        查询1条
        :param sql: sql语句
        :param params: 参数列表
        :return: 1条结果
        \'\'\'
        result =None
        #1.打开链接
        self.connect()
        # 2.执行查询
        self.cursor.execute(sql,params)
        # 3 逐行抓取
        result = self.cursor.fetchone()
        #4.释放资源
        self.close()
        return result

    def get_all(self, sql, params):
        \'\'\'
        查询所有
        :param sql: sql语句
        :param params: 参数列表
        :return: 1条结果
        \'\'\'
        result = ()
        self.connect()
        self.cursor.execute(sql, params)
        result = self.cursor.fetchall()
        self.close()
        return result


if __name__ == \'__main__\':
    # 实例化对象
    db =  MysqlHelper(\'localhost\', 3306, \'root\', \'root\', \'09c2\')
    #增加
    #insert into students values(default,\'张A\',\'男\',20,\'2020-11-05\',\'176\',\'山西\')
    \'\'\'
    sql = \'insert into students values(default,%s,%s,%s,%s,%s,%s)\'
    params=[\'张B\',\'男\',20,\'2020-11-05\',\'176\',\'山西\']
    num = db.my_execute(sql,params)
    print(num)
    \'\'\'
    # 查1条
    sql = \'select * from students where age =%s\'
    params=(12)
    result =db.get_one(sql,params) #((),())
    print(result)
    studetns = db.get_all(sql,params)
    for stu in studetns:
        print(f\'名字:{stu[1]}\')

 

错误

[SQL] insert into students values(default,\'张三\',\'男\',20,\'2020-11-05\',\'176\',\'山西\') 
[Err] 1062 - Duplicate entry \'张三\' for key \'name\' # 名字重复! Duplicate:重复!

学生管理系统

 

from MysqlHelper import  MysqlHelper #导入mysql工具类
from datetime import  datetime #导入日期模块

def add_stu():
    # 1.实例化工具类
    db = MysqlHelper(\'localhost\', 3306, \'root\', \'root\', \'09c2\')
    # 2. 调用增加方法
    #insert into students values(default,\'张A\',\'男\',20,\'2020-11-05\',\'176\',\'山西\')
    sql = \'insert into students values(default,%s,%s,%s,%s,%s,%s)\'
    params=[\'张D\',\'男\',20,datetime.now(),\'176\',\'山西\']
    num =db.my_execute(sql,params)
    return num


def del_stu(name):
    \'\'\'删除\'\'\'
    db = MysqlHelper(\'localhost\', 3306, \'root\', \'root\', \'09c2\')
    sql = \'delete from students where name =%s\'
    params=[name]
    num = db.my_execute(sql,params)
    return num

def update_stu(oldName,name,age,sex,phone,addr):
    db = MysqlHelper(\'localhost\', 3306, \'root\', \'root\', \'09c2\')
    sql =\'update students set name =%s,age=%s,sex=%s,phone=%s,addr=%s where name = %s\'
    params = (name,age,sex,phone,addr,oldName)
    return db.my_execute(sql,params)

def get_all():
    db = MysqlHelper(\'localhost\', 3306, \'root\', \'root\', \'09c2\')
    sql = \'select * from students\'
    students = db.get_all(sql,None)
    for stu in students:
        print(f\'名字:{stu[1]},性别:{stu[2]}\')

def get_by_name(name):
    db = MysqlHelper(\'localhost\', 3306, \'root\', \'root\', \'09c2\')
    sql = \'select * from students where name =%s\'
    params = (name)
    students = db.get_all(sql,params)
    for stu in students:
        print(f\'名字:{stu[1]},性别:{stu[2]}\')


if __name__ == \'__main__\':
    \'\'\'增加
    if add_stu() > 0:
        print(\'成功\')
    else:
        print(\'失败\')
    \'\'\'
    \'\'\' 删除
    if del_stu(\'张D\') >0:
        print(\'成功\')
    else:
        print(\'失败\')

    \'\'\'
    \'\'\'修改
    if update_stu(\'zhang\',"张小三",40,\'女\',\'110110\',\'陕西\')>0:
        print(\'修改成功\')
    else:
        print(\'失败\')
    \'\'\'
    del_stu(\'张D\')