At 03:07 PM 18/7/97 +0100, Philippa Tinsley wrote in response to Orycteropus
afer's comment (in part,
>Far too many automated systems define the fields
>used to record dates (acquisition dates, dates of manufacture, conservation
>dates, movement dates, etc.) as what is called a "date" type field internal
>to the database management system....This is almost always a BIG mistake):
>>I'm sorry, but I absolutely have to disagree with this.
(snip)
>>For example...
>>I want to get a list of all objects donated to the museum in the (UK) tax
year 1995/96
>>
>>If the field 'date acquired' is a date field, I can simply search for
everything from 6/4/1995 to 5/4/1996 and the system will find them all.
>>
>>However, if 'date acquired' is a character field (however manipulated), I
have to search for the following sets of characters '4/1995', '5/1995',
'6/1995', '7/1995', '8/1995', '9/1995', '10/1995', '11/1995', '12/1995',
'1/1996', '2/1996', '3/1996', '4/1996'.
>>Then I have to go through all the objects found by this search and
discount those with the characters '1/4/1995', '2/4/1995', '3/4/1995',
'4/4/1995', '5/4/1995', '6/4/1996' etc.
>>If I also included some objects in my database just with the year of
accession '1995', I'll have to make a separate search for these and decide
individually if I want to include them in my list.
If the dates are entered in a character field in year/ month/day format, you
simply search for everything from 1995/04/06 to 1996/04/05 (assuming that in
your example 6/4/1995 is in order month, day, year)--other than the
place-holding zeros, every bit as simple as searching a date field, but with
the ability to put in an unknown date (e.g., an unknown day within May 1995
can be entered as 1995/05/00), something not possible with date fields in
most database packages.
Cheers,
Art Harris
Laboratory for Environmental Biology, Centennial Museum
University of Texas at El Paso, El Paso, TX 79968-0519
[log in to unmask] (915) 747-6985
http://www.utep.edu/leb http://www.utep.edu/museum
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