Logging in system using MySQL database

1. Connect to MySQL database
2. We have one mem table with three sample records having userid, password and name columns.
3. Create one Tkinter window to ask user to enter userid and password.
4. Build the query and check the userid and password against the mem table and display appropriate message.

Connection to MySQL database & sample table

my_conn = create_engine("mysql+mysqldb://root:test@localhost/my_db")
#my_conn = create_engine("sqlite:///my_db_mem.db")

###  Start of Login window & process ######
def my_login():
    my_w_child=Toplevel(my_w) # Child window 
    my_w_child.geometry("220x140")  # Size of the window 
    my_w_child.title("www.plus2net.com")
    
    my_str1 = tk.StringVar()
    my_font1=('times', 18, 'bold')
    l1 = tk.Label(my_w_child,  textvariable=my_str1,font=my_font1 )
    l1.grid(row=1,column=2,columnspan=2) 
    my_str1.set("Login")
    
    my_str = tk.StringVar()
    l1 = tk.Label(my_w_child,  textvariable=my_str,width=10 )
    l1.grid(row=2,column=2) 
    my_str.set("Userid")
    userid_t = tk.Entry(my_w_child, width=17) # added one Entry box
    userid_t.grid(row=2,column=3)
        
    my_str2 = tk.StringVar()
    l2 = tk.Label(my_w_child, textvariable=my_str2 )
    l2.grid(row=3,column=2) 
    my_str2.set("Password")
    pw_t = tk.Entry(my_w_child, width=17) # added one Entry box
    pw_t.grid(row=3,column=3)
       
    b4 = tk.Button(my_w_child, text='Login', command=lambda:login())
    b4.grid(row=5,column=3)
    
    my_msg = tk.StringVar()
    l5 = tk.Label(my_w_child,  textvariable=my_msg)
    l5.grid(row=6,column=1,columnspan=4) 
    my_msg.set("Message here ")
    ## End of design of login window ##

    def login():
        flag_validation=True # set the flag 
        userid=userid_t.get()     # read userid
        pw=pw_t.get()             # read pw
        msg = ""
        # validation of entered data
        if(len(pw) <6): # length of name minimum 4 char
            flag_validation=False 
            msg = msg + "Password mininum 6 char  \n "
         # userid between 5 and 12    
        if(len(userid) <5 or len(userid)>12 or not userid.isalnum()):
            flag_validation=False 
            msg = msg + """Userid should not be less than 5 \n 
            & more than 12 \n Special chars not allowed"""
        else:
            my_query="SELECT password,name FROM mem WHERE userid=%s" 
            r_set=my_conn.execute(my_query,userid)
            r_set=r_set.fetchall()
            no=len(r_set)
            if(no != 1):
                flag_validation=False 
                msg = msg + "userid is not available  "
            elif(r_set[0][0] != pw):
                flag_validation=False 
                #print(r_set[0][0])  # print password 
                msg = msg + "Wrong Password "
            else:
                msg = "Welcome " + r_set[0][1]
        if(flag_validation):
            l5.config(fg='green')
        else:
            l5.config(fg='red')
        my_msg.set(msg)
        msg=''
        my_w_child.after(3000, lambda: my_msg.set(''))   
##### end login window #####