#!/usr/bin/wish
#code to make a Marquee
label .student_id_lab
pack .student_id_lab

set str "mysql is a database"
set substr ""

proc marquee {path str {len 0}} {
    if {[string length $str] == $len} return

    $path configure -text [string range $str 0 $len]
    after 500 [list marquee $path $str [incr len]]
}

marquee .student_id_lab $str