HELP me please!

R

rigby

Hi
I may be close to completing this database, but am having some trouble with
a table. I have 2 fields in this table which come up blank no matter what is
entered in the form related to the table. In the form, for the specific
controls which show up blank in the tables, these controls have expressions
built into them. I have tried building these expressions in the table's
fields, but it still wont work. I have one form control which looks up a
FullName from entering an ID number. the other expression calculates amount
of hours from 2 other controls of 'start time' & 'end time'. these
expressions work fine in the form, but wont post the results into the
appropriate table.

I do need them in the table to perform queries based on the answers, more so
for the time calculation. I have been told that i shouldnt need the answers
to appear in the table, but i really do. Please can someone help me with
this. I really do appreciate it.
Thank you in advance and have a Merry Christmas!

Kind Regards
Rigby
 
T

Tom Wickerath

Hi Rigby,
I do need them in the table to perform queries based on the answers, more
so for the time calculation. I have been told that i shouldnt need the answers
to appear in the table, but i really do.
Click to expand...

You were told correctly. You should be able to perform the calculation in
the query, without the need to store the result. Storing the results of a
calculation violates both 2nd and 3rd Normal Form of database design.
Consider the following quote from database design guru Michael Hernandez:

<Begin Quote>
The most important point for you to remember is that you will always
re-introduce data integrity problems when you de-Normalize your structures!
This means that it becomes incumbent upon you or the user to deal with this
issue. Either way, it imposes an unnecessary burden upon the both of you.
De-Normalization is one issue that you'll have to weigh and decide for
yourself whether the perceived benefits are worth the extra effort it will
take to maintain the database properly.
</End Quote>

From: Understanding Normalization by Michael Hernandez
http://www.datadynamicsnw.com/accesssig/downloads.htm
(See page 22 of the last download titled "Understanding Normalization")


Tom

http://www.access.qbuilt.com/html/expert_contributors.html
http://www.access.qbuilt.com/html/search.html
__________________________________________

:

Hi
I may be close to completing this database, but am having some trouble with
a table. I have 2 fields in this table which come up blank no matter what is
entered in the form related to the table. In the form, for the specific
controls which show up blank in the tables, these controls have expressions
built into them. I have tried building these expressions in the table's
fields, but it still wont work. I have one form control which looks up a
FullName from entering an ID number. the other expression calculates amount
of hours from 2 other controls of 'start time' & 'end time'. these
expressions work fine in the form, but wont post the results into the
appropriate table.

I do need them in the table to perform queries based on the answers, more so
for the time calculation. I have been told that i shouldnt need the answers
to appear in the table, but i really do. Please can someone help me with
this. I really do appreciate it.
Thank you in advance and have a Merry Christmas!

Kind Regards
Rigby
 
J

John Vinson

Hi
I may be close to completing this database, but am having some trouble with
a table. I have 2 fields in this table which come up blank no matter what is
entered in the form related to the table. In the form, for the specific
controls which show up blank in the tables, these controls have expressions
built into them. I have tried building these expressions in the table's
fields, but it still wont work. I have one form control which looks up a
FullName from entering an ID number. the other expression calculates amount
of hours from 2 other controls of 'start time' & 'end time'. these
expressions work fine in the form, but wont post the results into the
appropriate table.

I do need them in the table to perform queries based on the answers, more so
for the time calculation. I have been told that i shouldnt need the answers
to appear in the table, but i really do. Please can someone help me with
this. I really do appreciate it.
Thank you in advance and have a Merry Christmas!
Click to expand...

No. You DO NOT NEED THEM IN THE TABLE to perform the calculation.

Storing derived data such as this in your table accomplishes
three things: it wastes disk space; it wastes time (almost
any calculation will be MUCH faster than a disk fetch); and
most importantly, it risks data corruption. If one of the
underlying fields is subsequently edited, you will have data
in your table WHICH IS WRONG, and no automatic way to detect
that fact.

Just redo the calculation whenever you need it; if you need to do
something with DateDiff("n", [Start Time], [End Time]) in a further
calculation, just *include that expression in the calculation*. If you
want to use this time difference for sorting, or for searching, simply
include it in the query as a calculated field, and sort it or put
criteria on it.

John W. Vinson[MVP]
 
J

Joe

Re:Advice

I am trying to download Perl, I am unable to find a free compiler, can
anyone reccommend a site?
 
T

Tom Wickerath

Hi Joe,

This newsgroup is for questions and answers related to the database software
named "Microsoft Access" (new name is "Microsoft Office Access" for 2003).
Suggest that you find a different newsgroup to post your question to. To be
honest, I'm kind of stumped as to why you replied to this thread with such a
question.


Tom

http://www.access.qbuilt.com/html/expert_contributors.html
http://www.access.qbuilt.com/html/search.html
__________________________________________

:

Re:Advice

I am trying to download Perl, I am unable to find a free compiler, can
anyone reccommend a site?
 
M

masoumeh asgari

rigby said:
Hi
I may be close to completing this database, but am having some trouble
with
a table. I have 2 fields in this table which come up blank no matter what
is
entered in the form related to the table. In the form, for the specific
controls which show up blank in the tables, these controls have
expressions
built into them. I have tried building these expressions in the table's
fields, but it still wont work. I have one form control which looks up a
FullName from entering an ID number. the other expression calculates
amount
of hours from 2 other controls of 'start time' & 'end time'. these
expressions work fine in the form, but wont post the results into the
appropriate table.

I do need them in the table to perform queries based on the answers, more
so
for the time calculation. I have been told that i shouldnt need the
answers
to appear in the table, but i really do. Please can someone help me with
this. I really do appreciate it.
Thank you in advance and have a Merry Christmas!

Kind Regards
Rigby
Click to expand...
 
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