Simple ASP form validation - swapped?

Question

I am trying to do some very simple form validation checking for null or '' (empty) using a conditional, but when I submit my form with ALL BLANK FIELDS, it does the latter section of my code.

And when I fill out all of my fields it does that other part. So when they are blank, tell the user, which is the first section of the conditional, I have pasted my code below. Any suggestions on what I can do? Is it my "OR" or "AND"

if(((f_name <> null) or (f_name <> "")) or ((l_name <> null) or (l_name <> "")) or ((username <> null) or (username <> "")) or ((password <> null) or (password <> ""))) then
    'response.redirect("account_created.asp")
    response.write("You have not filled in all fields.")
else
    Set objConn = ConnectDB()
    query       = "INSERT INTO [user] (username,[password],f_name,l_name) VALUES ('"& username &"','"& password &"','"& f_name &"','"& l_name &"')"
    Set objs    = objConn.Execute(query)
    response.write(query)
    'Response.Redirect ("thankyou.asp")

end if

Thank you in advance,

Ryan

Answer 1

1. you do not need all the parentheses
2. if fname et al are the textboxes, you need fname.Text instead

Answer 2

In general it should be sufficient to check for empty string (such as f_name <> ""). I however usually do this with a trim and len. len(trim(f_name)) > 0. It takes care of all spaces. You should reconsider your parenthesis since they are not necessary. if len(trim(f_name)) > 0 or ... then