如何从在线（托管）mysql 数据库访问和编辑数据

Question

我正在制作一个类似聊天室的小程序，用户可以在其中注册、登录、发送和接收消息（在 Pycharm 中）。该程序在 mysql 数据库中包含用户详细信息，在 txt 文件中包含聊天记录我想在线托管它，以便不同的用户可以在不同的计算机上访问它，所以我必须对我的代码进行哪些更改（目前设计为在单台计算机上工作）

import pymysql
import random
def register(firstName,lastName,password,userName,emailId):
    db = pymysql.connect("localhost","root","pass","USERS")
    cursor = db.cursor()
    r=1
    while(r!=0):
        id = chr(random.randrange(65, 91)) + str(random.randrange(0, 10)) +str(random.randrange(0, 10))
        r = cursor.execute("SELECT * FROM UserData WHERE ID = '{}';".format(id))


    sql = "INSERT INTO UserData VALUES('{}','{}','{}','{}','{}','{}');".format(id,firstName,lastName,password,userName,emailId)
    try:
        cursor.execute(sql)
        print("Registration successful")
        file = open(id+'N.txt', 'a')
        db.commit()
    except Exception as e:
        print("Registration unsuccessful")
        print(str(e))
        db.rollback()
    db.close();


def displayNew(userId):
    file = open(userId+'N.txt', 'r')
    for message in file:
        print(message)
    open(userId+'N.txt', 'w').close()

def sendMessage(sender):
    receiver = input("RECEIVER's USERNAME : ")
    r = cursor.execute("SELECT * FROM UserData WHERE UserName = '{}';".format(receiver))
    if (r == 1):
        userInfo = cursor.fetchone()
        if(sender>userInfo[0]):
            chatfile = open(sender+'&'+userInfo[0]+'.txt', 'a')
        elif(sender<userInfo[0]):
            chatfile = open(userInfo[0]+'&'+sender+'.txt', 'a')
        newfile=open(userInfo[0]+'N.txt', 'a')
        message = input("MESSAGE(Single Line): ")
        cursor.execute("SELECT * FROM UserData WHERE ID = '{}';".format(sender))
        senderInfo = cursor.fetchone()
        senderName = senderInfo[4]
        chatfile.write(senderName+": "+message+"\n")
        newfile.write(senderName+": "+message+"\n")
    else:
        print("USER DOES NOT EXIST")
        retry=input("WANT TO RETRY(y/n)")
        if(retry=="y"):
            sendMessage(sender)

def oldMessage(receiver):
    sender = input("SENDER's USERNAME : ")
    r = cursor.execute("SELECT * FROM UserData WHERE UserName = '{}';".format(sender))
    if (r == 1):
        userInfo = cursor.fetchone()
        if(receiver>userInfo[0]):
            chatfile = open(receiver+'&'+userInfo[0]+'.txt', 'r')
        elif(receiver<userInfo[0]):
            chatfile = open(userInfo[0]+'&'+receiver+'.txt', 'r')
        for message in chatfile:
            print(message)

    else:
        print("USER DOES NOT EXIST")
        retry=input("WANT TO RETRY(y/n)")
        if(retry=="y"):
            sendMessage(sender)



while(True):
    db = pymysql.connect("localhost", "root", "dineshrashmi", "USERS")
    cursor = db.cursor()
    print("CHOICE 1: Login")
    print("CHOICE 2: Register")
    print("CHOICE 3: Exit")
    ch = int(input("Enter Your Choice : "))

    if(ch==1):
        userName = input("User Name : ")
        r=cursor.execute("SELECT * FROM UserData WHERE UserName = '{}';".format(userName))
        if(r==1):
            userInfo = cursor.fetchone()
            password = input("Password : ")
            if(userInfo[3]==password):
                cursor.execute("SELECT * FROM UserData WHERE UserName = '{}';".format(userName))
                print("WELCOME "+userInfo[1].upper()+" "+userInfo[2].upper())
                displayNew(userInfo[0])
                send=input("Do You Want To Send A Message(y/n) : ")
                if(send=="y"):
                    sendMessage(userInfo[0])
                view = input("Do You Want To View Old Message(y/n) : ")
                if (view == "y"):
                    oldMessage(userInfo[0])
                break
            else:
                print("INVALID PASSWORD")
        else:
            print("USER DOES NOT EXIST")
        print("\n")



    elif(ch==2):
        confirmPass = False
        userNameDuplicate = 1
        emailDuplicate = 1
        firstName = input("First Name : ")
        lastName = input("Last Name : ")

        while(userNameDuplicate!=0):
            userName = input("User Name : ")
            userNameDuplicate = int(cursor.execute("SELECT * FROM UserData WHERE UserName = '{}';".format(userName)))
            if (userNameDuplicate != 0):
                print("USER NAME ALREADY TAKEN")
                print("Try Again!")

        while(not confirmPass):
            password = input("Password : ")
            cpassword = input("Confirm Password : ")
            if(password==cpassword):
                confirmPass = True
            else:
                print("Password Mismatch")
                print("Try Again!")

        while (emailDuplicate != 0):
            emailId = input("Email : ")
            emailDuplicate = int(cursor.execute("SELECT * FROM UserData WHERE Email = '{}';".format(emailId)))
            if (emailDuplicate != 0):
                print("EMAIL ALREADY USED")
                print("Try Again!")

        regis = input("Register(y/n): ")
        if(regis=="y"):
            register(firstName,lastName,password,userName,emailId)
            print("\n")

    elif(ch==3):
        break

    else:
        print("INVALID CHOICE")
        print("\n")
    db.close();

Answer 1

从哪里开始？您可能可以采用多种方法，但到目前为止，最常见的方法是使用基于 HTML、CSS 和 JavaScript 的演示前端以及服务器端后端 -结尾写在Python.

因此，如果您还不知道 HTML、CSS 和 JavaScript，则需要学习这些技术。
您需要从 Internet 服务提供商 (ISP) 获得一个帐户，这样您才能拥有一个托管您的应用程序的网站。
理想情况下，ISP 将支持 Web Server Gateway Interface (WSGI) Python 应用程序。否则，您将必须按照 Common Gateway Interface (CGI) 规范进行编程。
您至少需要一个登录页面，该页面将输出一个 HTML form，该页面将接受用户 ID 和密码并登录用户并在 session 中维护登录信息.成功登录后，用户将重定向到您的页面，该页面将包含用于发送消息或查看旧消息的表单。
您希望将您的消息存储在数据库中。否则，您将需要实施 locking 机制来序列化对文件的访问。

我还没有解释什么是 HTML、CSS、JavaScript、WSGI、CGI 等等——这也需要长。这是给你调查的。

Answer 2

假设您有一个 MySql 数据库托管，其 IP 为 xxx.xxx.xx.xx 并且它有一个用户（例如 root，密码 PASS）和一个数据库（例如 USERS).

使用 PyMySQL，您可以通过将 'localhost' 替换为代码中的 IP 来连接到它。

示例：

...
db = pymysql.connect("xxx.xxx.xx.xx","root","pass","UERS")
cursor = db.cursor()
...

确保您设置数据库实例的方式允许从任何地方（* 或最好从您想连接到它的地方）

您可以使用以下命令使用 MySQL client 验证连接：

mysql -h xxx.xxx.xx.xx -u root -pPASS

# To see the list of databases after getting connected
>show databases;

如何从在线（托管）mysql 数据库访问和编辑数据

How to access and edit data from online(hosted) mysql database

python

mysql-python

python-3.7