Re: advice in model design - principally

[_Sebastian_]

Hi Bruno,

thanks for you search hints, maybe mine (database table layout...) was
not the best choice for what I was looking for.
I will give it a go again with your suggestions.

Thx

seb

On Jan 16, 1:29 am, bruno desthuilliers
 wrote:
> On 15 jan, 13:05, _Sebastian_  wrote:
>
> > Hy all,
>
> > I'm trying to replicate a existing project database as a conceptual
> > test.
>
> > I started off with creating a few models and I thought about ways on
> > how I could link and/or organise them. As I'm just starting to learn
> > django and python and my basic database knowledge is restricted to MS
> > products I want to get some basic things right.
>
> > I'm talking not about the technical bits on how to write modules,
> > fields and stuff I am thinking about how to organise tables, the
> > underlying principles and rules.
>
> This is nothing specific to django (or almost, cf below). Google for
> "relational model" and "relational database design",  and "normal
> form". Once you have a normalized data model, there may be a couple
> Django-specific stuff - mostly, Django doesn't (yet) support compound
> primary keys (so you'll have to use a surrogate key), and some
> contribs (like generic) requires an integer primarry key, so better to
> stick to it even if you do have a natural primary key.
>
> > I head a search and came 
> > acrosshttp://publib.boulder.ibm.com/infocenter/idshelp/v10/index.jsp?topic=...
> > which I am reading now but I was wondering if you know a better site
> > to read about this sort of question?
>
> After a very quick look, it seems that the section about design might
> be a good start.
--~--~-~--~~~---~--~~
You received this message because you are subscribed to the Google Groups 
"Django users" group.
To post to this group, send email to django-users@googlegroups.com
To unsubscribe from this group, send email to 
django-users+unsubscr...@googlegroups.com
For more options, visit this group at 
http://groups.google.com/group/django-users?hl=en
-~--~~~~--~~--~--~---

Re: advice in model design - principally

[bruno desthuilliers]

On 15 jan, 13:05, _Sebastian_  wrote:
> Hy all,
>
> I'm trying to replicate a existing project database as a conceptual
> test.
>
> I started off with creating a few models and I thought about ways on
> how I could link and/or organise them. As I'm just starting to learn
> django and python and my basic database knowledge is restricted to MS
> products I want to get some basic things right.
>
> I'm talking not about the technical bits on how to write modules,
> fields and stuff I am thinking about how to organise tables, the
> underlying principles and rules.

This is nothing specific to django (or almost, cf below). Google for
"relational model" and "relational database design",  and "normal
form". Once you have a normalized data model, there may be a couple
Django-specific stuff - mostly, Django doesn't (yet) support compound
primary keys (so you'll have to use a surrogate key), and some
contribs (like generic) requires an integer primarry key, so better to
stick to it even if you do have a natural primary key.

> I head a search and came across 
> http://publib.boulder.ibm.com/infocenter/idshelp/v10/index.jsp?topic=...
> which I am reading now but I was wondering if you know a better site
> to read about this sort of question?

After a very quick look, it seems that the section about design might
be a good start.


--~--~-~--~~~---~--~~
You received this message because you are subscribed to the Google Groups 
"Django users" group.
To post to this group, send email to django-users@googlegroups.com
To unsubscribe from this group, send email to 
django-users+unsubscr...@googlegroups.com
For more options, visit this group at 
http://groups.google.com/group/django-users?hl=en
-~--~~~~--~~--~--~---

Re: advice in model design - principally

[Kenneth Gonsalves]

On Thursday 15 Jan 2009 6:04:13 pm _Sebastian_ wrote:
> Could you elaborate on what you mean with 'then break them a bit for
> speed'?

well, 3 normal forms is the ideal - but we live in a real world. So after 
normalising the database, it is often found that repeating a field, or adding 
a field that can be calculated from existing fields in a table speeds up 
things enormously without significantly compromising database integrity. So 
we do it. It may not be necessary in a smaller database, but may be needed in 
a bigger one. 

-- 
regards
KG
http://lawgon.livejournal.com

--~--~-~--~~~---~--~~
You received this message because you are subscribed to the Google Groups 
"Django users" group.
To post to this group, send email to django-users@googlegroups.com
To unsubscribe from this group, send email to 
django-users+unsubscr...@googlegroups.com
For more options, visit this group at 
http://groups.google.com/group/django-users?hl=en
-~--~~~~--~~--~--~---

Re: advice in model design - principally

[_Sebastian_]

Kenneth,

thank you for your reply.

Could you elaborate on what you mean with 'then break them a bit for
speed'?

 - seb

On Jan 15, 11:22 pm, Kenneth Gonsalves  wrote:
> On Thursday 15 Jan 2009 5:35:56 pm _Sebastian_ wrote:
>
> > I head a search and came across
> >http://publib.boulder.ibm.com/infocenter/idshelp/v10/index.jsp?topic=...
> >bm.ddi.doc/ddi27.htm
>
> basically you would need to read up on the first three normal forms, try to
> implement them and then break them a bit for speed if needed. Any site that
> describes the normal forms is ok for that - this one seems ok.
>
> --
> regards
> KGhttp://lawgon.livejournal.com
--~--~-~--~~~---~--~~
You received this message because you are subscribed to the Google Groups 
"Django users" group.
To post to this group, send email to django-users@googlegroups.com
To unsubscribe from this group, send email to 
django-users+unsubscr...@googlegroups.com
For more options, visit this group at 
http://groups.google.com/group/django-users?hl=en
-~--~~~~--~~--~--~---

Re: advice in model design - principally

[Kenneth Gonsalves]

On Thursday 15 Jan 2009 5:35:56 pm _Sebastian_ wrote:
> I head a search and came across
> http://publib.boulder.ibm.com/infocenter/idshelp/v10/index.jsp?topic=/com.i
>bm.ddi.doc/ddi27.htm

basically you would need to read up on the first three normal forms, try to 
implement them and then break them a bit for speed if needed. Any site that 
describes the normal forms is ok for that - this one seems ok.

-- 
regards
KG
http://lawgon.livejournal.com

--~--~-~--~~~---~--~~
You received this message because you are subscribed to the Google Groups 
"Django users" group.
To post to this group, send email to django-users@googlegroups.com
To unsubscribe from this group, send email to 
django-users+unsubscr...@googlegroups.com
For more options, visit this group at 
http://groups.google.com/group/django-users?hl=en
-~--~~~~--~~--~--~---