GET and POST for backend 

@app.route('/register', methods=["POST", "GET"])
def register():
    if request.method == 'POST':
        username = request.form['username']
        password = request.form['password']
        if check_user(username, password):
            return "user already exist"
        else:
            register_user(username, password)
            return redirect('/')
    
@app.route('/login', methods=["POST", "GET"])
def login():
    if request.method == 'POST':
        username = request.form['username']
        password = request.form['password']
        print(check_user(username, password))
        if check_user(username, password):
            session['username']=username

            return redirect('/home')
        else:
            return "Wrong Username or Password"
    
@app.route('/home', methods=["POST","GET"])
def home():
    if 'username' in session:
        return render_template("index.html", username=session['username'])
    else:
        return "Wrong Credentials"

Table for create and read operation