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Home -> Community -> Mailing Lists -> Oracle-L -> RE: how to generate the output w/o using temp table
and so my list gets longer ...
Thanks Lex.
Henry
-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org]On Behalf Of Lex de Haan
Sent: Monday, August 02, 2004 3:23 PM
To: oracle-l_at_freelists.org
Subject: RE: how to generate the output w/o using temp table
of course, I knew someone had to bring that up :-) well, in short, they are the "enemies" ... there has been a fierce academic battle in the ISO world between two "camps" about this issue of temporal data. and since the ISO standardization process is based upon achieving consensus, the idea of standardizing temporal data was put on hold a while ago. it was supposed to become part 7 of the SQL:2003 standard, but if you have access to the ANSI/ISO SQL standard (it is not freely accessible, unfortunately) you will find out that part 7 simply doesn't exist -- there is a gap in the parts numbering.
If you really, really, really like this topic very much, you should of course read *both* books and then choose which approach you prefer.
The management summary is that Chris Date (cum suis) basically states that you don't need to treat time as something different, because the relational model is capable to treat time as a regular attribute -- you only need some additional operators in your relational language. If you know Chris Date and his opinion about the relational model, I guess you are not surprised ;-)
Kind regards,
Lex.
-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org]On Behalf Of Poras, Henry R.
Sent: Monday, August 02, 2004 19:44
To: 'oracle-l_at_freelists.org'
Subject: RE: how to generate the output w/o using temp table
Lex,
How does this compare to the Richard Snodgrass book 'Developing
Time-Oriented
Database Applications in SQL'
(http://www.cs.arizona.edu/people/rts/tdbbook.pdf)?
Henry
-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org]On Behalf Of Lex de Haan
Sent: Monday, August 02, 2004 1:29 PM
To: oracle-l_at_freelists.org
Subject: RE: how to generate the output w/o using temp table
as an aside, if you are interested in some theory behind this type of problems, the following book is a must: Chris date, Hugh Darwen, and Nikos Lorentzos: "Temporal Data and the Relational Model" Morgan Kaufmann Publishers, ISBN 1-55860-855-9.
they introduce the concept of "packing" and "unpacking" data over the time dimension -- which is the generalization of the issue here.
Kind regards,
Lex.
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org]On Behalf Of Daniel Fink
Sent: Monday, August 02, 2004 18:01
To: oracle-l_at_freelists.org
Subject: Re: how to generate the output w/o using temp table
Somehow, you need to iterate through a list of months between the start and end dates and find all records that fall within that range. If you have a calendar type table, you can use that. If not, you have to get creative. I've included some code below (part stolen from other posters, part from my own twisted mind). *IF* the number of months requested is greater that the number of rows in the vacation table, it will *not* work. A better solution would be to code it in PL/SQL or another language.
Regards,
Daniel Fink
FAQ is at http://www.freelists.org/help/fom-serve/cache/1.htmlput 'unsubscribe' in the subject line.
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