No need to be heronic, here is the code, thx for your help!
<html>
<body>
<%
Set adoConnection = server.CreateObject("ADODB.Connection"

Set adoRecordset = server.CreateObject("ADODB.Recordset"

Dim iLength,iFieldCount
adoConnection.Open ("DRIVER={Microsoft Access Driver (*.mdb)}; DBQ=" & Server.MapPath("\pekap\db\Database.mdb"

)
iFieldCount = 0
FirstHalfSQL = "insert into [professors] ("
SecondHalfSQL = "

Values ("
EndSQL = "

"%>
<!--Óõíäåóç ìå âáóç -->
<%
varidiotita = request.form("idiotita"

If varidiotita <> "" then
iFieldCount = iFieldCount + 1
varidiotita = Replace(varidiotita, "'", "''"

If iFieldCount = 1 Then
FirstHalfSQL = FirstHalfSQL & "[idiotita]"
Else
FirstHalfSQL = FirstHalfSQL & ",[idiotita]"
End If
If iFieldCount = 1 Then
SecondHalfSQL = SecondHalfSQL & "'" & varidiotita & "'"
Else
SecondHalfSQL = SecondHalfSQL & ",'" & varidiotita & "'"
End If
End If
%>
<%
vardieyth = request.form("dieyth"

If vardieyth <> "" then
iFieldCount = iFieldCount + 1
vardieyth = Replace(vardieyth, "'", "''"

If iFieldCount = 1 Then
FirstHalfSQL = FirstHalfSQL & "[dieyth]"
Else
FirstHalfSQL = FirstHalfSQL & ",[dieyth]"
End If
If iFieldCount = 1 Then
SecondHalfSQL = SecondHalfSQL & "'" & vardieyth & "'"
Else
SecondHalfSQL = SecondHalfSQL & ",'" & vardieyth & "'"
End If
End If
%>
<%
vartilefono = request.form("tilefono"

If vartilefono <> "" then
iFieldCount = iFieldCount + 1
vartilefono = Replace(vartilefono, "'", "''"

If iFieldCount = 1 Then
FirstHalfSQL = FirstHalfSQL & "[tilefono]"
Else
FirstHalfSQL = FirstHalfSQL & ",[tilefono]"
End If
If iFieldCount = 1 Then
SecondHalfSQL = SecondHalfSQL & "'" & vartilefono & "'"
Else
SecondHalfSQL = SecondHalfSQL & ",'" & vartilefono & "'"
End If
End If
%>
<%
vartaxkod = request.form("taxkod"

If vartaxkod <> "" then
iFieldCount = iFieldCount + 1
vartaxkod = Replace(vartaxkod, "'", "''"

If iFieldCount = 1 Then
FirstHalfSQL = FirstHalfSQL & "[taxkod]"
Else
FirstHalfSQL = FirstHalfSQL & ",[taxkod]"
End If
If iFieldCount = 1 Then
SecondHalfSQL = SecondHalfSQL & "'" & vartaxkod & "'"
Else
SecondHalfSQL = SecondHalfSQL & ",'" & vartaxkod & "'"
End If
End If
%>
<%
varperioxi = request.form("perioxi"

If varperioxi <> "" then
iFieldCount = iFieldCount + 1
varperioxi = Replace(varperioxi, "'", "''"

If iFieldCount = 1 Then
FirstHalfSQL = FirstHalfSQL & "[perioxi]"
Else
FirstHalfSQL = FirstHalfSQL & ",[perioxi]"
End If
If iFieldCount = 1 Then
SecondHalfSQL = SecondHalfSQL & "'" & varperioxi & "'"
Else
SecondHalfSQL = SecondHalfSQL & ",'" & varperioxi & "'"
End If
End If
%>
<%
varpolis = request.form("polis"

If varpolis <> "" then
iFieldCount = iFieldCount + 1
varpolis = Replace(varpolis, "'", "''"

If iFieldCount = 1 Then
FirstHalfSQL = FirstHalfSQL & "[polis]"
Else
FirstHalfSQL = FirstHalfSQL & ",[polis]"
End If
If iFieldCount = 1 Then
SecondHalfSQL = SecondHalfSQL & "'" & varpolis & "'"
Else
SecondHalfSQL = SecondHalfSQL & ",'" & varpolis & "'"
End If
End If
%>
<%
varemail = request.form("email"

If varemail <> "" then
iFieldCount = iFieldCount + 1
varemail = Replace(varemail, "'", "''"

If iFieldCount = 1 Then
FirstHalfSQL = FirstHalfSQL & ""
Else
FirstHalfSQL = FirstHalfSQL & ",[email]"
End If
If iFieldCount = 1 Then
SecondHalfSQL = SecondHalfSQL & "'" & varemail & "'"
Else
SecondHalfSQL = SecondHalfSQL & ",'" & varemail & "'"
End If
End If
%>
<%
varlname = request.form("lname"

If varlname <> "" then
iFieldCount = iFieldCount + 1
varlname = Replace(varlname, "'", "''"

If iFieldCount = 1 Then
FirstHalfSQL = FirstHalfSQL & "[lname]"
Else
FirstHalfSQL = FirstHalfSQL & ",[lname]"
End If
If iFieldCount = 1 Then
SecondHalfSQL = SecondHalfSQL & "'" & varlname & "'"
Else
SecondHalfSQL = SecondHalfSQL & ",'" & varlname & "'"
End If
End If
%>
<%
varfname = request.form("fname"

If varfname <> "" then
iFieldCount = iFieldCount + 1
varfname = Replace(varfname, "'", "''"

If iFieldCount = 1 Then
FirstHalfSQL = FirstHalfSQL & "[fname]"
Else
FirstHalfSQL = FirstHalfSQL & ",[fname]"
End If
If iFieldCount = 1 Then
SecondHalfSQL = SecondHalfSQL & "'" & varfname & "'"
Else
SecondHalfSQL = SecondHalfSQL & ",'" & varfname & "'"
End If
End If
%>
<% adoRecordset.ActiveConnection = AdoConnection
SQLInsert = FirstHalfSQL & SecondHalfSQL & EndSQL
if SQLInsert <> "insert into [professors] () Values ()" then
on error resume next
call adoRecordset.Open(SQLInsert)
if err.number = -2147467259 then
response.redirect("[URL unfurl="true"]http://www.ppols.gr/contact.htm?duplicatedata=true"

[/URL]
end if
on error goto 0
else
response.redirect("[URL unfurl="true"]http://www.ppols.gr/contact.htm?nodata=true"

[/URL]
end if
response.redirect("[URL unfurl="true"]http://www.ppols.gr/contact.htm?successful=true"

[/URL]
%>
</BODY>
</HTML>