Re: django/Data Base Advice

[Chris Kavanagh]

On Jan 5, 6:40 pm, Petite Abeille  wrote:
> On Jan 6, 2012, at 12:13 AM, Chris Kavanagh wrote:
>
> > I believe, thanks to your (previous) post, I was confused as to the
> > difference between SQL and Database in general. I had thought learning
> > SQL was learning database design. When in actuality, it's just the
> > language used to access databases. I need to study database concepts
> > and design.
>
> There are two main aspects to SQL:  Data Definition Language (DDL [1]) and 
> Data Manipulation Language (DML [2]).
>
> DDL is was you design database with (create table, etc). DML is what you 
> interact database with (select, update, etc).
>
> In the same way as it's rather helpful to understand HTTP itself to build a 
> web application, it's rather essential to understand database design if you 
> build a database, irrespectively of sugar coating (ORM [3], MVC, and other 
> TLA).
>
> Learn about normalization [3].
>
> Take a look at SQLite to get started [4][5].
>
> In the meantime:
>
> Double-thinking in 
> SQLhttp://explainextended.com/2009/07/12/double-thinking-in-sql/
>
> Also:http://browsertoolkit.com/fault-tolerance.png
>
> [1]http://en.wikipedia.org/wiki/Data_Definition_Language
> [2]http://en.wikipedia.org/wiki/Data_Manipulation_Language
> [3]http://en.wikipedia.org/wiki/Database_normalization
> [4]http://www.sqlite.org/
> [5]http://www.sqlite.org/lang.html

Thank you for the advice Petite. I will check out those links also.

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Re: django/Data Base Advice

[Petite Abeille]

On Jan 6, 2012, at 12:13 AM, Chris Kavanagh wrote:

> I believe, thanks to your (previous) post, I was confused as to the
> difference between SQL and Database in general. I had thought learning
> SQL was learning database design. When in actuality, it's just the
> language used to access databases. I need to study database concepts
> and design.

There are two main aspects to SQL:  Data Definition Language (DDL [1]) and Data 
Manipulation Language (DML [2]).

DDL is was you design database with (create table, etc). DML is what you 
interact database with (select, update, etc).

In the same way as it's rather helpful to understand HTTP itself to build a web 
application, it's rather essential to understand database design if you build a 
database, irrespectively of sugar coating (ORM [3], MVC, and other TLA).

Learn about normalization [3].

Take a look at SQLite to get started [4][5].

In the meantime:

Double-thinking in SQL
http://explainextended.com/2009/07/12/double-thinking-in-sql/

Also:
http://browsertoolkit.com/fault-tolerance.png

[1] http://en.wikipedia.org/wiki/Data_Definition_Language
[2] http://en.wikipedia.org/wiki/Data_Manipulation_Language
[3] http://en.wikipedia.org/wiki/Database_normalization
[4] http://www.sqlite.org/
[5] http://www.sqlite.org/lang.html

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Re: django/Data Base Advice

[Chris Kavanagh]

On Jan 5, 2:54 pm, Lie Ryan  wrote:
> On 01/06/2012 02:35 AM, Dennis Lee Bieber wrote:
>
> > Django's models are just a means to define those independent of engine
> > specific notation.
>
> while introducing django-specific notation, which generally maps more
> neatly to the theoretical foundation than SQL (while SQL maps more
> neatly to the implementation of database system).
>
> In particular, in django the concept of primary keys is implemented as
> autoincrementing integers is well hidden from you, and django's foreign
> keys is a full-fledged objects instead of integers with a few restrictions.

I believe, thanks to your (previous) post, I was confused as to the
difference between SQL and Database in general. I had thought learning
SQL was learning database design. When in actuality, it's just the
language used to access databases. I need to study database concepts
and design.

And I think that probably concludes my question to this post. While
knowing SQL will be helpful, I believe I need to learn some about
general database concepts.

THANKS TO EVERYONE who helped me!!! It's very much appreciated, and I
do mean that sincerely. Thanks for taking your time to help a novice.

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Re: django/Data Base Advice

[Chris Kavanagh]

On Jan 5, 10:35 am, Dennis Lee Bieber  wrote:
> On Wed, 4 Jan 2012 17:50:41 -0800 (PST), Chris Kavanagh

>
>         While my comment regarding MVC has been shot down by others, I'll
> still stand by the comment regarding relational database theory: the
> first three Codd Normal Forms and related concepts. These are
> independent of the actual database engine used in the end. Knowing what
> to put into a relation (in formal theory, what folks commonly call a
> "table" is the "relation" -- not the links from one table to another)...
> Django's models are just a means to define those independent of engine
> specific notation.
>
>         SQL, originally (when it was IBM's Sequel), was a pure query
> language sort of combining bits of relational algebra and relational
> calculus. It was supposed to be usable even with hierarchical or network
> database systems (though the backend code generator had to be fairly
> complex, compared to simple flat-file systems which many relational
> engines work as -- MySQL, dBase, Foxpro all use individual files for
> each relation [table]).
>
>         Knowing SQL in general can give some insights into what Django is
> doing behind the scenes for the 1<>many and many<>many linkages.
> --
>         Wulfraed                 Dennis Lee Bieber         AF6VN
>         wlfr...@ix.netcom.com    HTTP://wlfraed.home.netcom.com/

After reading the posts concerning whether it's an MVC or  MTV here's
what the book says: "Django follows the MVC pattern closely enough
that it CAN be called an MVC framework."

I just thought I'd post that to be fair. . .Thanks Dennis.

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Re: django/Data Base Advice

[Chris Kavanagh]

On Jan 5, 3:58 am, Lie Ryan  wrote:
> On 01/05/2012 01:01 PM, Chris Kavanagh wrote:
>
>
> While learning SQL could be helpful for writing fine-tuned SQL queries,
> IMO it doesn't really help much to design an effective database. To
> design an effective database schema, you need to learn about database,
> not (just) SQL. Learn about basic database concept such as primary and
> foreign keys, data modelling, and normalization (up to 3rd or 4th level
> normalization is generally good enough for all practical purposes).

Ok, I just learned something. I THOUGHT SQL WAS learning Database!!!
So, SQL is really just the language used to interact with databases,
not really the database itself??? I need to Google database concepts
and learn that, not just SQL?? I assume that's what you're saying Lie.

And THANKS for the advice.

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Re: django/Data Base Advice

[Lie Ryan]

On 01/06/2012 02:35 AM, Dennis Lee Bieber wrote:

Django's models are just a means to define those independent of engine
specific notation.


while introducing django-specific notation, which generally maps more 
neatly to the theoretical foundation than SQL (while SQL maps more 
neatly to the implementation of database system).


In particular, in django the concept of primary keys is implemented as 
autoincrementing integers is well hidden from you, and django's foreign 
keys is a full-fledged objects instead of integers with a few restrictions.


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Re: django/Data Base Advice

[Lie Ryan]

On 01/05/2012 01:01 PM, Chris Kavanagh wrote:



On Jan 4, 8:20 am, Andre Terra  wrote:

I'm sorry, folks, but I'll have to *vehemently **disagree *with a lot of
what has been said in this thread. To the OP, I'm sorry I didn't reply any
sooner.

No, you *don't need *to go reading about what MVC means. Django is a
*MTV *framework,
not *MVC*. There are similarities, but the differences are enough to
confuse your head if this is your first time with either one. You should
definitely stick to Django Book[1] for a definition on what Models, Views
and Templates are. Everyone who says otherwise is wrong. Once you're
comfortable with Django, feel free to explore other frameworks so you can
weigh the pros and cons yourself.

No, you *don't need* to read the Python PEP on DB-API (?!?!). I'll go as
far as say you *shouldn't.* Not now and not for any time in the foreseeable
feature. You won't need to write raw SQL in Django until you've reached a
big bottleneck, and one that can't be solved in any other way. Writing raw
SQL is exactly what Django wants you to *stop* doing. The ORM doesn't only
exist in order to speed up development. It provides a layer of abstraction
that also allows for easy refactoring and code improvement. SQL is not as
flexible.

The only PEP you need to read right away is PEP 8[2]. Learn it, love it,
memorize it, use it. Everything else will only bring marginal benefits at
such an early stage in the learning curve while also carrying a level of
complexity that will most likely be a hindrance to your overall experience.

Follow the tutorials and the django book (while outdated, most of it should
work fine). When asking questions, remember to paste a *full *traceback and
code examples. It might not make any sense to you, but eventually you'll
learn your way around it. #django on freenode is rather helpful for quick
questions and, if you know how to ask your question[3], this mailing list
will also prove useful.

Finally, If you need some pointers on HTML/CSS/JS, start with the HTML5
boilerplate[4] "framework". Everyone and their grandma seem to be using it
nowadays. It will give you enough of a starting point that should make
cross-browser compatibility as painless as possible, and should get you
going in a flash.

I hope you find my advice convincing enough so that it may prevent you from
hurting your own learning process. I wish you only the best!

Good luck and happy coding!

André Terra

[1]http://djangobook.com/en/2.0/chapter01/
[2]http://www.python.org/dev/peps/pep-0008/
[3]https://code.djangoproject.com/wiki/UsingTheMailingList
[4]http://html5boilerplate.com/



Thanks for the advice Andre. . .Ok here's the crux of my original
question, that I didn't ask very well. How can I learn to make my own
Models, without knowing SQL?? In the book, at the beginning of Chp 5,
Models, there's a note that says something like, "you don't strictly
need to know SQL to follow along, but it sure helps." Since I have no
database experience, I took that quote seriously.

To be honest, after looking through the Models chapter in the book,
and on djangoproject.com, it doesn't look too complicated. The Model
Class Fields seem pretty simple. But then again, if I had to design a
model from scratch, I think I would have a problem. That's why I
thought learning SQL, just to learn a little about databases might be
helpful.


While learning SQL could be helpful for writing fine-tuned SQL queries, 
IMO it doesn't really help much to design an effective database. To 
design an effective database schema, you need to learn about database, 
not (just) SQL. Learn about basic database concept such as primary and 
foreign keys, data modelling, and normalization (up to 3rd or 4th level 
normalization is generally good enough for all practical purposes).


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Re: django/Data Base Advice

[kenneth gonsalves]

On Wed, 2012-01-04 at 11:20 -0200, Andre Terra wrote:
> I'm sorry, folks, but I'll have to vehemently disagree with a lot of
> what has been said in this thread. To the OP, I'm sorry I didn't reply
> any sooner.
> 
> No, you don't need to go reading about what MVC means. Django is a MTV
> framework, not MVC. There are similarities, but the differences are
> enough to confuse your head if this is your first time with either
> one. You should definitely stick to Django Book[1] for a definition on
> what Models, Views and Templates are. Everyone who says otherwise is
> wrong. Once you're comfortable with Django, feel free to explore other
> frameworks so you can weigh the pros and cons yourself.
> 
> No, you don't need to read the Python PEP on DB-API (?!?!). I'll go as
> far as say you shouldn't. Not now and not for any time in the
> foreseeable feature. You won't need to write raw SQL in Django until
> you've reached a big bottleneck, and one that can't be solved in any
> other way. Writing raw SQL is exactly what Django wants you to stop
> doing. The ORM doesn't only exist in order to speed up development. It
> provides a layer of abstraction that also allows for easy refactoring
> and code improvement. SQL is not as flexible.
> 
> The only PEP you need to read right away is PEP 8[2]. Learn it, love
> it, memorize it, use it. Everything else will only bring marginal
> benefits at such an early stage in the learning curve while also
> carrying a level of complexity that will most likely be a hindrance to
> your overall experience.
> 
> Follow the tutorials and the django book (while outdated, most of it
> should work fine). When asking questions, remember to paste a full
> traceback and code examples. It might not make any sense to you, but
> eventually you'll learn your way around it. #django on freenode is
> rather helpful for quick questions and, if you know how to ask your
> question[3], this mailing list will also prove useful.
> 
> Finally, If you need some pointers on HTML/CSS/JS, start with the
> HTML5 boilerplate[4] "framework". Everyone and their grandma seem to
> be using it nowadays. It will give you enough of a starting point that
> should make cross-browser compatibility as painless as possible, and
> should get you going in a flash.
> 
> I hope you find my advice convincing enough so that it may prevent you
> from hurting your own learning process. I wish you only the best!
> 
I fully agree - except for the caveat that reading up a bit on normal
forms will not hurt. Django cannot design your db for you - you have to
do it yourself.
-- 
regards
Kenneth Gonsalves

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Re: django/Data Base Advice

[Chris Kavanagh]

On Jan 4, 10:36 am, Javier Guerra Giraldez  wrote:
> On Wed, Jan 4, 2012 at 8:20 AM, Andre Terra  wrote:
> > No, you don't need to go reading about what MVC means. Django is a MTV
> > framework, not MVC. There are similarities, but the differences are enough
> > to confuse your head if this is your first time with either one.
>
> I agree, i'd even say forget about MVC!
>
> this is a pet peeve of mine, MVC was originally defined as a _modular_
> design for OOP GUI frameworks.  There, for every complex user
> interaction, you define three modules (usually a class each, but not
> necessarily): the Model that keeps the immediate data in an
> OOP-friendly way, the View that presents it using a GUI, and the
> Controller, that receives events and modifies the data in the Model,
> and (sometimes) tells the View to update or change modes.
>
> Code reuse gets enhanced, since you frequently can use the same view
> for different parts of the program, and the same model might be
> presented in different ways by different views.  configurability also
> becomes a desirable trait, that lets use the same view or model code
> for different objects, just by creating differently-configured
> instances.
>
> many years later, when the 'three-tier' web architecture (storage
> layer, business intelligence layer and presentation layer) was
> well-known and viewed by some as overly complex for 'dynamic' web
> apps, the MVC acronym got reused, but now it's a _layered_
> architecture for web apps: there you design a model layer (that
> presents storage with a nice API), a View layer (comprising of some
> data-gathering logic and templates to generate HTML) and a Controller
> layer that.. is anything else needed? well, lets say it handles
> URLs.
>
> As you can see, web MVC is totally different from GUI MVC, and it's a
> very ill-fitting description, since it's about layers and not modules,
> and the controller is so loosely defined (especially when compared to
> the crisp definitions in GUI MVC) that every framework defines it
> differently and in many cases add unnecessary complexity instead of
> removing it (some PHP frameworks are particularly guilty of this).
>
> the MTV architecture in Django is far cleaner, since it acknowledges
> that there's no controller (the URL handling part is too simple to be
> a layer), and makes very explicit the separation between
> data-gathering (view functions/classes) and presentation (templates)
>
> --
> Javier

Thank You Javier.

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Re: django/Data Base Advice

[Chris Kavanagh]

On Jan 4, 9:16 am, Venkatraman S  wrote:
> On Wed, Jan 4, 2012 at 6:50 PM, Andre Terra  wrote:
> > You won't need to write raw SQL in Django until you've reached a big
> > bottleneck, and one that can't be solved in any other way. Writing raw SQL
> > is exactly what Django wants you to *stop* doing. The ORM doesn't only
> > exist in order to speed up development. It provides a layer of abstraction
> > that also allows for easy refactoring and code improvement. SQL is not as
> > flexible.
>
> I havent read the rest of the thread; but I agree with what you mentioned
> in your reply, with suitable reservations on the above comment.
>
> SQL is highly flexible provided you know to write good sql (its like the
> way Russell mentions 'It Depends' :P ); atleast i have been writing sqls
> for the past 8 years and i find it easy to write them when the
> relationships are complex. I come from a database family, and writing
> highly database cohesive apps is what i have been doing for quiet sometime.
> And it is very much given that, if you are writing a reporting app with
> 30-40 tables, then you would end up writing raw sqls(this is NOT the norm
> for a non-reporting app).
>
> But when i mention the above, i also see that django ORM produces some
> really nice SQLs for mediocre usecases, i.e, i am yet to stumble on a case
> wherein the SQL produced by the ORM wouldnt be the same(tuned) as what i
> would write. So Kudos over there. In my spare time, i always mess around
> with hierarchical queries and what not to see what the django-orm produces
> and i must say that it has been a good learning experience.
>
> To cut verbiage/or to summarize...and...Not to confuse the OP : yes, as
> Andre mentions, if you do not have any advance use cases; go ahead with
> django orm. It wouldnt give you any sleepless nights.
>
> -Venkat

Thanks for the advice Venkat.

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Re: django/Data Base Advice

[Chris Kavanagh]

On Jan 4, 8:20 am, Andre Terra  wrote:
> I'm sorry, folks, but I'll have to *vehemently **disagree *with a lot of
> what has been said in this thread. To the OP, I'm sorry I didn't reply any
> sooner.
>
> No, you *don't need *to go reading about what MVC means. Django is a
> *MTV *framework,
> not *MVC*. There are similarities, but the differences are enough to
> confuse your head if this is your first time with either one. You should
> definitely stick to Django Book[1] for a definition on what Models, Views
> and Templates are. Everyone who says otherwise is wrong. Once you're
> comfortable with Django, feel free to explore other frameworks so you can
> weigh the pros and cons yourself.
>
> No, you *don't need* to read the Python PEP on DB-API (?!?!). I'll go as
> far as say you *shouldn't.* Not now and not for any time in the foreseeable
> feature. You won't need to write raw SQL in Django until you've reached a
> big bottleneck, and one that can't be solved in any other way. Writing raw
> SQL is exactly what Django wants you to *stop* doing. The ORM doesn't only
> exist in order to speed up development. It provides a layer of abstraction
> that also allows for easy refactoring and code improvement. SQL is not as
> flexible.
>
> The only PEP you need to read right away is PEP 8[2]. Learn it, love it,
> memorize it, use it. Everything else will only bring marginal benefits at
> such an early stage in the learning curve while also carrying a level of
> complexity that will most likely be a hindrance to your overall experience.
>
> Follow the tutorials and the django book (while outdated, most of it should
> work fine). When asking questions, remember to paste a *full *traceback and
> code examples. It might not make any sense to you, but eventually you'll
> learn your way around it. #django on freenode is rather helpful for quick
> questions and, if you know how to ask your question[3], this mailing list
> will also prove useful.
>
> Finally, If you need some pointers on HTML/CSS/JS, start with the HTML5
> boilerplate[4] "framework". Everyone and their grandma seem to be using it
> nowadays. It will give you enough of a starting point that should make
> cross-browser compatibility as painless as possible, and should get you
> going in a flash.
>
> I hope you find my advice convincing enough so that it may prevent you from
> hurting your own learning process. I wish you only the best!
>
> Good luck and happy coding!
>
> André Terra
>
> [1]http://djangobook.com/en/2.0/chapter01/
> [2]http://www.python.org/dev/peps/pep-0008/
> [3]https://code.djangoproject.com/wiki/UsingTheMailingList
> [4]http://html5boilerplate.com/
>

Thanks for the advice Andre. . .Ok here's the crux of my original
question, that I didn't ask very well. How can I learn to make my own
Models, without knowing SQL?? In the book, at the beginning of Chp 5,
Models, there's a note that says something like, "you don't strictly
need to know SQL to follow along, but it sure helps." Since I have no
database experience, I took that quote seriously.

To be honest, after looking through the Models chapter in the book,
and on djangoproject.com, it doesn't look too complicated. The Model
Class Fields seem pretty simple. But then again, if I had to design a
model from scratch, I think I would have a problem. That's why I
thought learning SQL, just to learn a little about databases might be
helpful.
>

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Re: django/Data Base Advice

[Chris Kavanagh]

On Jan 3, 11:40 pm, Dennis Lee Bieber  wrote:
> On Tue, 3 Jan 2012 19:30:37 -0800 (PST), Chris Kavanagh
>
>  wrote:
>
> >Well, I was referring to the database part, but really I need to learn
> >more about web development too. I know HTML, CSS, JavaScript vaguely,
> >and that's about it. Since I LUV Python (like I said, a beginner in
> >Python) I figured Django would be a good place to start learning web
> >dev.Am I wrong?? You're saying INSTEAD OF Django, learn an MVC? I was
> >under the impression Django was an MVC, am I wrong??
>
>         I think the advice was to learn MVC /as concepts/ (or theory), NOT
> as a particular implementation. Once you understand how MVC separates
> the parts of an application then you can examine how Django implements
> MVC.
>
>         I'd add the same comment with regards to database -- don't learn "A"
> relational database system, but instead learn the concepts of relational
> databases (which means learning at least the first three Codd Normal
> Forms ). Then add SQL in general (inner/left/right joins, sorting,
> etc.).
>
>         Then, if you need it (you intend raw SQL access rather than using an
> object-relational manager (ORM -- SQLAlchemy, for example), study the
> Python PEP that discusses the DB-API, since many of the basic database
> adapters implement that interface (at this point you may need to learn
> the specifics of the database adapter you are using: MySQLdb uses %s for
> positional placeholder, whereas SQLite3 uses ?).
>
> --
>         Wulfraed                 Dennis Lee Bieber         AF6VN
>         wlfr...@ix.netcom.com    HTTP://wlfraed.home.netcom.com/

Thanks for the advice Dennis! BTW, any relation to Justin??? Sorry,
couldn't resist!!!

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Re: django/Data Base Advice

[Javier Guerra Giraldez]

On Wed, Jan 4, 2012 at 8:20 AM, Andre Terra  wrote:
> No, you don't need to go reading about what MVC means. Django is a MTV
> framework, not MVC. There are similarities, but the differences are enough
> to confuse your head if this is your first time with either one.

I agree, i'd even say forget about MVC!

this is a pet peeve of mine, MVC was originally defined as a _modular_
design for OOP GUI frameworks.  There, for every complex user
interaction, you define three modules (usually a class each, but not
necessarily): the Model that keeps the immediate data in an
OOP-friendly way, the View that presents it using a GUI, and the
Controller, that receives events and modifies the data in the Model,
and (sometimes) tells the View to update or change modes.

Code reuse gets enhanced, since you frequently can use the same view
for different parts of the program, and the same model might be
presented in different ways by different views.  configurability also
becomes a desirable trait, that lets use the same view or model code
for different objects, just by creating differently-configured
instances.

many years later, when the 'three-tier' web architecture (storage
layer, business intelligence layer and presentation layer) was
well-known and viewed by some as overly complex for 'dynamic' web
apps, the MVC acronym got reused, but now it's a _layered_
architecture for web apps: there you design a model layer (that
presents storage with a nice API), a View layer (comprising of some
data-gathering logic and templates to generate HTML) and a Controller
layer that.. is anything else needed? well, lets say it handles
URLs.

As you can see, web MVC is totally different from GUI MVC, and it's a
very ill-fitting description, since it's about layers and not modules,
and the controller is so loosely defined (especially when compared to
the crisp definitions in GUI MVC) that every framework defines it
differently and in many cases add unnecessary complexity instead of
removing it (some PHP frameworks are particularly guilty of this).


the MTV architecture in Django is far cleaner, since it acknowledges
that there's no controller (the URL handling part is too simple to be
a layer), and makes very explicit the separation between
data-gathering (view functions/classes) and presentation (templates)

-- 
Javier

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Re: Django/Data Base Advice

[Andre Terra]

On Wed, Jan 4, 2012 at 12:16 PM, Venkatraman S  wrote:

> SQL is highly flexible provided you know to write good sql (its like the
> way Russell mentions 'It Depends' :P ); atleast i have been writing sqls
> for the past 8 years and i find it easy to write them when the
> relationships are complex. I come from a database family, and writing
> highly database cohesive apps is what i have been doing for quiet sometime.
> And it is very much given that, if you are writing a reporting app with
> 30-40 tables, then you would end up writing raw sqls(this is NOT the norm
> for a non-reporting app).



You, sir, are correct.

SQL is a powerful tool, and one that must indeed be used if we are to write
enterprise-grade applications. I should have probably picked a better word
than "flexible". In reality, SQL's great flexibility is precisely what
enables the creation of tools like the ORM. With enough time and knowledge,
you can use SQL to slice your data in any way you can imagine, as long as
we're talking about relational information.

What I meant to emphasize is that hard coding your queries in python
strings will most likely mean they will break as soon as you do some
refactoring, schema migration and many other possible changes in your
database. This is why raw SQL, while incredibly powerful, can be skipped in
most everyday cases, especially for a beginner. The ORM allows for a good
deal of tweaking that can be used to speed up the most common kinds of
queries.

That said, learning SQL is a fundamental step in becoming a "full-fledged"
Django developer, as dealing with databases will your everyday task. It is
also the only way you will understand what's happening "behind the
curtains". It is a necessary step in building scalable apps and keeping
them as light as possible.


TL;DR I shouldn't have said SQL isn't flexible; the lack of flexibility
lies in hard coded strings, but that can even impact the python side of a
Django app.


Cheers,
AT

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Re: django/Data Base Advice

[Venkatraman S]

On Wed, Jan 4, 2012 at 6:50 PM, Andre Terra  wrote:

> You won't need to write raw SQL in Django until you've reached a big
> bottleneck, and one that can't be solved in any other way. Writing raw SQL
> is exactly what Django wants you to *stop* doing. The ORM doesn't only
> exist in order to speed up development. It provides a layer of abstraction
> that also allows for easy refactoring and code improvement. SQL is not as
> flexible.
>

I havent read the rest of the thread; but I agree with what you mentioned
in your reply, with suitable reservations on the above comment.

SQL is highly flexible provided you know to write good sql (its like the
way Russell mentions 'It Depends' :P ); atleast i have been writing sqls
for the past 8 years and i find it easy to write them when the
relationships are complex. I come from a database family, and writing
highly database cohesive apps is what i have been doing for quiet sometime.
And it is very much given that, if you are writing a reporting app with
30-40 tables, then you would end up writing raw sqls(this is NOT the norm
for a non-reporting app).

But when i mention the above, i also see that django ORM produces some
really nice SQLs for mediocre usecases, i.e, i am yet to stumble on a case
wherein the SQL produced by the ORM wouldnt be the same(tuned) as what i
would write. So Kudos over there. In my spare time, i always mess around
with hierarchical queries and what not to see what the django-orm produces
and i must say that it has been a good learning experience.

To cut verbiage/or to summarize...and...Not to confuse the OP : yes, as
Andre mentions, if you do not have any advance use cases; go ahead with
django orm. It wouldnt give you any sleepless nights.

-Venkat

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Re: django/Data Base Advice

[Andre Terra]

I'm sorry, folks, but I'll have to *vehemently **disagree *with a lot of
what has been said in this thread. To the OP, I'm sorry I didn't reply any
sooner.

No, you *don't need *to go reading about what MVC means. Django is a
*MTV *framework,
not *MVC*. There are similarities, but the differences are enough to
confuse your head if this is your first time with either one. You should
definitely stick to Django Book[1] for a definition on what Models, Views
and Templates are. Everyone who says otherwise is wrong. Once you're
comfortable with Django, feel free to explore other frameworks so you can
weigh the pros and cons yourself.

No, you *don't need* to read the Python PEP on DB-API (?!?!). I'll go as
far as say you *shouldn't.* Not now and not for any time in the foreseeable
feature. You won't need to write raw SQL in Django until you've reached a
big bottleneck, and one that can't be solved in any other way. Writing raw
SQL is exactly what Django wants you to *stop* doing. The ORM doesn't only
exist in order to speed up development. It provides a layer of abstraction
that also allows for easy refactoring and code improvement. SQL is not as
flexible.

The only PEP you need to read right away is PEP 8[2]. Learn it, love it,
memorize it, use it. Everything else will only bring marginal benefits at
such an early stage in the learning curve while also carrying a level of
complexity that will most likely be a hindrance to your overall experience.

Follow the tutorials and the django book (while outdated, most of it should
work fine). When asking questions, remember to paste a *full *traceback and
code examples. It might not make any sense to you, but eventually you'll
learn your way around it. #django on freenode is rather helpful for quick
questions and, if you know how to ask your question[3], this mailing list
will also prove useful.

Finally, If you need some pointers on HTML/CSS/JS, start with the HTML5
boilerplate[4] "framework". Everyone and their grandma seem to be using it
nowadays. It will give you enough of a starting point that should make
cross-browser compatibility as painless as possible, and should get you
going in a flash.

I hope you find my advice convincing enough so that it may prevent you from
hurting your own learning process. I wish you only the best!



Good luck and happy coding!

André Terra


[1] http://djangobook.com/en/2.0/chapter01/
[2] http://www.python.org/dev/peps/pep-0008/
[3] https://code.djangoproject.com/wiki/UsingTheMailingList
[4] http://html5boilerplate.com/

On Wed, Jan 4, 2012 at 2:40 AM, Dennis Lee Bieber wrote:

> On Tue, 3 Jan 2012 19:30:37 -0800 (PST), Chris Kavanagh
>  wrote:
>
> >
> >Well, I was referring to the database part, but really I need to learn
> >more about web development too. I know HTML, CSS, JavaScript vaguely,
> >and that's about it. Since I LUV Python (like I said, a beginner in
> >Python) I figured Django would be a good place to start learning web
> >dev.Am I wrong?? You're saying INSTEAD OF Django, learn an MVC? I was
> >under the impression Django was an MVC, am I wrong??
> >
> I think the advice was to learn MVC /as concepts/ (or theory), NOT
> as a particular implementation. Once you understand how MVC separates
> the parts of an application then you can examine how Django implements
> MVC.
>
>I'd add the same comment with regards to database -- don't learn "A"
> relational database system, but instead learn the concepts of relational
> databases (which means learning at least the first three Codd Normal
> Forms ). Then add SQL in general (inner/left/right joins, sorting,
> etc.).
>
>Then, if you need it (you intend raw SQL access rather than using an
> object-relational manager (ORM -- SQLAlchemy, for example), study the
> Python PEP that discusses the DB-API, since many of the basic database
> adapters implement that interface (at this point you may need to learn
> the specifics of the database adapter you are using: MySQLdb uses %s for
> positional placeholder, whereas SQLite3 uses ?).
>
> --
>Wulfraed Dennis Lee Bieber AF6VN
>wlfr...@ix.netcom.comHTTP://wlfraed.home.netcom.com/
>
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Re: django/Data Base Advice

[Chris Kavanagh]

On Jan 3, 5:58 pm, Python_Junkie 
wrote:
> Don't want to confuse you on the database topic, but thought I would
> add my 2 cents.
>
> You asked how to go about learning how to design / utilize the
> database within the context of django.
>
> I just wanted to point out that the django tutorial will point you
> down the road of implementing a database abstraction layer, the ORM.
> With the object relational model (ORM), you can create tables and
> relationships and extract or insert/update data from those tables.
>
> The ORM is fine to work with, however, just be aware that reading up
> on database tutorials, sql queries, table design, relational models
> etc,
> may confuse you a bit when trying to equate those concepts to the ORM.
>
> My own preference is to use sql calls using python directly rather
> than using the ORM in django.   Just another (abstraction) layer to
> learn, and it is a matter
> of opinion the value it adds to the speed, or efficiency of the
> development process
>
> On Jan 3, 4:09 am, wC  wrote:
>
>
> Thank you for the advice!  Now when you say the ORM, are we talking about the 
> API for my particular database?? Interacting with it using SQL commands 
> within the API?? Forgive my ignorance.

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Re: django/Data Base Advice

[Chris Kavanagh]

On Jan 3, 4:09 am, wC  wrote:
> Chris,
>
> I think was somehow in the same stage not so long ago... Here is how I went
> about it:
>
> 1. I watched a db-class video from time to time (teaches you what joins are
> etcetera). Using the ORM without db knowledge is ok if efficiency is not
> your main concern. Sooner or later you have to make database design choices
> and only relying on the community is going to slow you down. Good advice is
> expensive (time or effort).
> 2. Having read the docs on djangoproject.com (which are huge), I read
> djangobook.com, then I started building my own apps following some of the
> tutorials fromhttps://code.djangoproject.com/wiki/Tutorials. I made myself
> a todo-app, for instance. There are about three or four tutorials for that
> and each of them adds some knowledge (the nettuts one is for true
> beginners). If you work on you app a bit you'll gain knowledge in testing,
> migrating, implementing design and much more. I always asked myself 'does
> my program solve a problem'. If it does not, you will get lost pretty
> quickly.
> 3. ?
>
> Not sure what the next step would be? Deploy a small website? Use third
> party OS code? Any suggestions?
>
> Cheers
> wC

Thanks man, I will follow your advice!

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Re: django/Data Base Advice

[Chris Kavanagh]

On Jan 2, 8:49 pm, Victor Hooi  wrote:
> Hi,
>
> Do you mean learning more about Django in general, or about the
> models.py/database portion specifically?
>
> If you haven't done much web-development before, or used any MVC
> frameworks, I suggest you start by reading up on those - there's plenty of
> guides to that online.
>
> In terms of learning database theory, I'd suggest either "Database Design
> for Mere Mortals"
> (http://www.amazon.com/Database-Design-Mere-Mortals-Hands/dp/0201694719),
> or "Database Design with UML and SQL" (http://www.tomjewett.com/dbdesign/).
>
> Cheers,
> Victor

Well, I was referring to the database part, but really I need to learn
more about web development too. I know HTML, CSS, JavaScript vaguely,
and that's about it. Since I LUV Python (like I said, a beginner in
Python) I figured Django would be a good place to start learning web
dev.Am I wrong?? You're saying INSTEAD OF Django, learn an MVC? I was
under the impression Django was an MVC, am I wrong??

And Thanks for the help Victor!

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Re: django/Data Base Advice

[Chris Kavanagh]

On Jan 2, 7:38 pm, Mike Dewhirst  wrote:
> On 3/01/2012 10:59am, Chris Kavanagh wrote:
>
>
>
>
>
>
>
>
>
>
>
> > On Jan 2, 6:57 pm, Chris Kavanagh  wrote:
> >> I'm new to django&  programming in general. I know the basics of
> >> Python. Anyways, going through the djangoproject tutorial, I came to
> >> the part where you edit the polls/models.py, and this is where I need
> >> advice.
>
> >> I understand roughly what's going in when we write the script in
> >> models.py, however if I had to create something like this on my own, I
> >> wouldn't know where to begin. Obviously I have no .db experience, but
> >> I get the gist of the different types of fields django uses. The
> >> question is, how do I go about learning this?? Do I need to go through
> >> an SQL tutorial to better understand how this works??
>
> >> Thanks in advance for ANY help!
>
> I read somewhere that it takes about 10,000 hours of
> (learning/training/practice/work) to achieve mastery in any area
> requiring complex skills and knowhow. Playing a musical instrument,
> writing complex database systems for the web, air traffic control - you
> name it.
>
> I think you need to bite the bullet and slog your way through the
> tutorial. Don't expect to understand too much the first time but learn
> to follow the written instructions *slavishly* until it actually works.
>
> Then get yourself a copy of The Definitive Guide to Django by Adrian
> Holovaty and Jacob Kaplan-Moss and work through that.
>
> Finally tackle a small project of your own and make that work. Google
> will help you answer most of your questions.
>
> Good luck
>
> Mike
>
>
Thanks so much for the advice Mike. Actually I have the book, and I'm
going through the tutorial now. When I came to the database part, I
realized I didn't know a thing about them. So how could I write Python
code that would interact with a database?? So, I figured there had to
be someway to learn this stuff. I wasn't sure what to study to learn/
get better at it. . .After going through that chp in the book, and
looking quickly at an SQL Tutorial, I think I have a better
understanding of what I need to do.

Again, thanks so much for the advice. It's much appreciated!

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Re: django/Data Base Advice

[Python_Junkie]

Don't want to confuse you on the database topic, but thought I would
add my 2 cents.

You asked how to go about learning how to design / utilize the
database within the context of django.

I just wanted to point out that the django tutorial will point you
down the road of implementing a database abstraction layer, the ORM.
With the object relational model (ORM), you can create tables and
relationships and extract or insert/update data from those tables.


The ORM is fine to work with, however, just be aware that reading up
on database tutorials, sql queries, table design, relational models
etc,
may confuse you a bit when trying to equate those concepts to the ORM.

My own preference is to use sql calls using python directly rather
than using the ORM in django.   Just another (abstraction) layer to
learn, and it is a matter
of opinion the value it adds to the speed, or efficiency of the
development process







On Jan 3, 4:09 am, wC  wrote:
> Chris,
>
> I think was somehow in the same stage not so long ago... Here is how I went
> about it:
>
> 1. I watched a db-class video from time to time (teaches you what joins are
> etcetera). Using the ORM without db knowledge is ok if efficiency is not
> your main concern. Sooner or later you have to make database design choices
> and only relying on the community is going to slow you down. Good advice is
> expensive (time or effort).
> 2. Having read the docs on djangoproject.com (which are huge), I read
> djangobook.com, then I started building my own apps following some of the
> tutorials fromhttps://code.djangoproject.com/wiki/Tutorials. I made myself
> a todo-app, for instance. There are about three or four tutorials for that
> and each of them adds some knowledge (the nettuts one is for true
> beginners). If you work on you app a bit you'll gain knowledge in testing,
> migrating, implementing design and much more. I always asked myself 'does
> my program solve a problem'. If it does not, you will get lost pretty
> quickly.
> 3. ?
>
> Not sure what the next step would be? Deploy a small website? Use third
> party OS code? Any suggestions?
>
> Cheers
> wC

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Re: django/Data Base Advice

[wC]

Chris,

I think was somehow in the same stage not so long ago... Here is how I went 
about it:

1. I watched a db-class video from time to time (teaches you what joins are 
etcetera). Using the ORM without db knowledge is ok if efficiency is not 
your main concern. Sooner or later you have to make database design choices 
and only relying on the community is going to slow you down. Good advice is 
expensive (time or effort).
2. Having read the docs on djangoproject.com (which are huge), I read 
djangobook.com, then I started building my own apps following some of the 
tutorials from https://code.djangoproject.com/wiki/Tutorials. I made myself 
a todo-app, for instance. There are about three or four tutorials for that 
and each of them adds some knowledge (the nettuts one is for true 
beginners). If you work on you app a bit you'll gain knowledge in testing, 
migrating, implementing design and much more. I always asked myself 'does 
my program solve a problem'. If it does not, you will get lost pretty 
quickly.
3. ?

Not sure what the next step would be? Deploy a small website? Use third 
party OS code? Any suggestions?

Cheers
wC

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Re: django/Data Base Advice

[Mike Dewhirst]

On 3/01/2012 10:59am, Chris Kavanagh wrote:



On Jan 2, 6:57 pm, Chris Kavanagh  wrote:

I'm new to django&  programming in general. I know the basics of
Python. Anyways, going through the djangoproject tutorial, I came to
the part where you edit the polls/models.py, and this is where I need
advice.

I understand roughly what's going in when we write the script in
models.py, however if I had to create something like this on my own, I
wouldn't know where to begin. Obviously I have no .db experience, but
I get the gist of the different types of fields django uses. The
question is, how do I go about learning this?? Do I need to go through
an SQL tutorial to better understand how this works??

Thanks in advance for ANY help!


I read somewhere that it takes about 10,000 hours of 
(learning/training/practice/work) to achieve mastery in any area 
requiring complex skills and knowhow. Playing a musical instrument, 
writing complex database systems for the web, air traffic control - you 
name it.


I think you need to bite the bullet and slog your way through the 
tutorial. Don't expect to understand too much the first time but learn 
to follow the written instructions *slavishly* until it actually works.


Then get yourself a copy of The Definitive Guide to Django by Adrian 
Holovaty and Jacob Kaplan-Moss and work through that.


Finally tackle a small project of your own and make that work. Google 
will help you answer most of your questions.


Good luck

Mike




BTW, I'm using Winxp, django1.3.1 and Sqlite3 (with Python2.7)



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Re: django/Data Base Advice

[Chris Kavanagh]

On Jan 2, 6:57 pm, Chris Kavanagh  wrote:
> I'm new to django & programming in general. I know the basics of
> Python. Anyways, going through the djangoproject tutorial, I came to
> the part where you edit the polls/models.py, and this is where I need
> advice.
>
> I understand roughly what's going in when we write the script in
> models.py, however if I had to create something like this on my own, I
> wouldn't know where to begin. Obviously I have no .db experience, but
> I get the gist of the different types of fields django uses. The
> question is, how do I go about learning this?? Do I need to go through
> an SQL tutorial to better understand how this works??
>
> Thanks in advance for ANY help!

BTW, I'm using Winxp, django1.3.1 and Sqlite3 (with Python2.7)

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django/Data Base Advice

[Chris Kavanagh]

I'm new to django & programming in general. I know the basics of
Python. Anyways, going through the djangoproject tutorial, I came to
the part where you edit the polls/models.py, and this is where I need
advice.

I understand roughly what's going in when we write the script in
models.py, however if I had to create something like this on my own, I
wouldn't know where to begin. Obviously I have no .db experience, but
I get the gist of the different types of fields django uses. The
question is, how do I go about learning this?? Do I need to go through
an SQL tutorial to better understand how this works??

Thanks in advance for ANY help!

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