[AccessD] On DB Bloat, Bad DB Design, and various

Jürgen Welz jwelz at hotmail.com
Tue May 25 12:05:56 CDT 2004


I wouldn't suggest that setting text fields to a length of 255 is incorrect 
except where length is part of a validation rule that you want to enforce at 
the database table level.  However, designing a table with fields whose 
total allowable size exceeds a size that can be saved and not taking steps 
to validate and handle an oversize record is bad design.  Neglecting to 
provide the user with a meaningful error message and allowing him to choose 
which fields to truncate or at least dumping all his text into a memo field 
with notification that certain fields were arbitrarily truncated (if that is 
how you handle it) is a failure to properly design an application.

Developers need to be aware of limitations and need to handle them, either 
in an error handler or in this instance, by providing additional one to one 
tables to allow for the full size of record possible.  I have found that 
users don't report all errors and many developers do not use an error log to 
track actual issues.  Then there are those who blithely throw in an 'On 
Error Resume Next' and blame failed entries on users.

It is not terribly difficult to bind a text display control alternately to 
memo field or to a text field as required, though it is more problematic in 
a continuous form.  It is usually sufficient to set an unbound text field to 
display the concatenated contents of two bound fields that are hidden and 
set their contents in code in the after update of the unbound display/input 
control.  I have found that leaving the first 20 characters in the text 
field and everything after the first 20 in the memo field, when it is 
required, allows one to kind of sort and index on the text field even though 
it may it operates functionally as a memo.


Ciao
Jürgen Welz
Edmonton, Alberta
jwelz at hotmail.com

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