Yeah, Wook, there are two places where you can specify maxlenght, the textbox itself, in which case input will stop when it reaches the maximum lenght, it doesn't generate any errors here, and the DB fields also can have a maxlenght, this will generate errors if the inserted data is bigger than the field allowance.
If you really need to have limits like (100), you must parse user input before inserting it into the DB, here's an example:
<%
dbALLOWANCE = 100
parsedMSG = Request.Form("txtMSG")
If Len(parsedMSG) > dbALLOWANCE Then
Response.Write "Too Big!"
End If
%>
Hope it helps.