[web2py] how to write if else in controller in web2py

[anil manikyam]

def login():
    if db((db.table1.username)== request.vars.visitor_name).select():
        redirect(URL('index'))
    else:
        print 'invalid statement'
    return dict()


in this username and visitor_name are compared if correct redirect to
index page it is work very well

but if those are not equal else part is not printed why?

i want code for this