When you develop dynamic webpages with multiple tables, how many of you create physical relationships and how masny of you ignore it and simply create virtual relationships in the front-end query development stage?

I myself have never done this since i stopped using oracle and access, and i was wondering if there are obvious advantages? what does everyone think?

this could be an interesting string for newbies and experienced developers alike.

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Julio Mellado

PHP | MySQL | UD4

ICQ: 19735247
MSN:

virtual

<font face='Tahoma'>errrrr, what's the difference? (newbie)</font id='Tahoma'>

If on an Intranet, relationship is on the page. If on the web relationship is bulit in DB (I use SQL 7 and Oracle).



Regards
Vince

Response.write("The best line of code you can ever use"

VBScript | ASP | HTML | SQL | Oracle | Hosting

Motomaxx:

Data Relationships allow you have parent/child relationships for records. For example in a CD Music website you might have one band with many albums, and each album has many songs on it. Relationships enable you to refer records to a parental or "master" table. This allows you to list certain related records depending on the parent record.

The difference in practice, is this: some database systems (Access, Oracle SQL++) are designed so that you physically state the relationships between two fields in separate tables (e.g. AlbumID would be common between the album and the tracks it contains). On DB applications which are designed to be implemented on local or networked environments (not the internet) relationships like that are useful, as you can use the physical links to easily create parent/child forms using the links.

However, in my personal experience, i have never used physical links in PHP/ASP environment, as most of the record relationships i have used are coded in the front end using PHP and URL GET variables, straight into the SQL queries.

Both methods have their advantages, i'd like to know what people do in general, as i'd love to find out if there would be any advantages in using physical data relationaships in web development application environments.

-- Julio

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Julio Mellado

PHP | MySQL | UD4

ICQ: 19735247
MSN:

hi poolio,

thanks for the explanation, that makes a lot of sense now! no wonder i didn't really know the difference (all of my database design experience is from the web.), i have been using virtual relationships as i just pass variables in the URL.

very interesting, i have just been setting up simple Access databases and have not gotten into anything deeper yet, i have MS-SQL7 and am looking forward to exploiting that beyond what Access can do!

Previously i have used Virtual.

But logically im thinking would it not be better to setup physicall relations?
E.g in SQL server you could be able to set a parent child relationship which will automatically delete all child objects. Is this possible? if so then i would think that using phsyicall relationships would be better.


I know i do all of this manually delete the Parent then delete all instances of the child. Its a bit cumbersome.

yeah, i'm not really sure how the physical relationships would be transported over to ASP/PHP pages. I'd imagine you'd have to code some kind of script anyway. I know what in access/vba the physical relatiosanhips are extremely useful as they allow to manupulate data easily.

i have never tried it in a scripted page envrironment... i'd love to hear from someone who's tried it.

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Julio Mellado

PHP | MySQL | UD4

ICQ: 19735247
MSN:

I use physical relationships, this ensures that you can't delete a part of a related record without an error occuring, which should cut down on orphaned bits of records and general rubbish in the DB.

Regards

Owen.

Multiple Parameter UD4 / Access 2000 Database Search Tutorial:
www.tdsf.co.uk/tdsfdemo

Do you use Access? What other advantages does it have when you use ASP or PHP pages? Does it have any effect on the way data is displayed or the way it behaves?

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Julio Mellado

PHP | MySQL | UD4

ICQ: 19735247
MSN: