How can i add multiple screens in kivymd?

Question

I am building a password manager app using kivymd.I created a login screen window with two input fields and three buttons to login, register a nd clear text.I also created a database so that user login credentials can be verified. All is working fine and for now I assigned my login button a command to check for login credentials in database and if correct then show text on a lable as "Successfully loggined".

Now what I want is to create a new window /screen so that I can display the users their data(urls,usernames,passwords) and i want that if user clicks login button then after verifying all credentials in database, program should switch to new screen.

Can any one help?

BTW I CREATED A SEPERATE KV FILE FOR THIS PROJECT

from kivymd.app import MDApp
import sqlite3

class MainApp(MDApp):
    def build(self):
        return Builder.load_file("login.kv")
    
    
    def login(self):            
        conn = sqlite3.connect("master.db")
        cur = conn.cursor()
        
        
        user = self.root.ids.user.text
        password = self.root.ids.password.text
        if user=="" or password=="" :  
           self.root.ids.error.markup=True
           self.root.ids.error.text = "[b][color=#f50539]materuser & masterpassword required ![/b][/color]" 
           
        else:           
            cur.execute("SELECT rowid , *FROM master_database WHERE master_users = ?", (user,))
            
            c=cur.fetchone()
            conn.commit()
            conn.close()
        
            if c==None:
                self.root.ids.error.markup=True
                
                self.root.ids.error.text = f"No data for [color=#f50539][b]{user}[/b][/color]\nKindly register for [color=#f50539][b]new user ![/b][/color]" 

                                                    
            else:
                    
                    if c[2] == password:
                        self.root.ids.error.markup=True
                        self.root.ids.error.text = "[b]Successfully Loginned[b]"
                        
                        
                    else:
                        self.root.ids.error.markup=True
                        self.root.ids.error.text = "[b]Incorrect Password ![b]"  
                      
MainApp.run() 

#KV file----->

MDCard:
    size_hint:None,None
    size:400,500
    pos_hint:{"center_x":.5,"center_y":.5}
    elevation:10
    padding:25
    spacing:25

    orientation:"vertical"
    
    
    MDRoundFlatButton:
        id : log_in
        text:"LOG IN"   
        font_size:12
        pos_hint:{"center_x":.5}
        on_release:app.login()

Answer 1

Please Provide the full code > BTW you can add screens on kivy file using

ScreenManager:
    Main:
    WelcomeScreen:

here main contains the login screen and when the user clicks the login button on it , the values are checked by your login() function and when all the things are correct switch to the second screen self.kv.get_screen('welcomescreen').manager.current = "welcomescreen"