from  kivymd.app import MDApp
from kivy.lang import Builder
import mysql.connector
class MainApp(MDApp):
    mydb = mysql.connector.connect(
        host="localhost",
        user="root",
        passwd="test123",
        database="first_db"
    )
    c=mydb.cursor()
    def build(self):
        self.theme_cls.theme_style = "Dark"
        self.theme_cls.primary_palette = "BlueGray"
        return Builder.load_file("login.kv")
    def trydecotate(self):
        pass
    def register(self,login,password):
        self.c.execute(f"INSERT into users values('{login.text}','{password.text}')")
        self.mydb.commit()
        login.text=password.text=""
MainApp().run()

Screen:
    MDCard:
        size_hint:None,None
        size:300,400
        pos_hint:{"center_x":0.5,"center_y":0.5}
        elevation:10
        padding:25
        spacing:25
        orientation:'vertical'
        MDTextFieldRound:
            id:login
            hint_text:"username"
            icon_right:"account"
            post_hint:{"center_x": 0.5,"center_y":0.5}
            font_size:18
            size_hint:1,None
            width:200
        MDTextFieldRound:
            id:password
            hint_text:"password"
            icon_right:"eye-off"
            post_hint:{"center_x": 0.5,"center_y":0.5}
            font_size:18
            size_hint:1,None
            width:200
            password:True
        MDRoundFlatButton:
            text:"Login"
            font_size:12
            pos_hint:{"center_x":0.5}
            on_release:app.log_in(login,password)
        MDRoundFlatButton:
            text:"Register"
            font_size:12
            pos_hint:{"center_x":0.5}
            on_release:app.register(login,password)
        Widget:
            size_hint_y:None
            height:10]