how to validate "user already present" before submitting the form with security

[shuchitaumehta]

hello

i want 2 validate user already present in mysql db or not before submitting the form

1. i can take all db values in javascript variable / cookie
   but its not secure coz user can see this

pls help me

thank you

[bpat1434]

The user would be able to see data during the post as well. The only way to check it is to actually send the current username via an AJAX request to check it, or check it during form processing.

[leatherback]

big question is.. Why would you want to!?