Why we do double work?

[sender]

When we develop a package using front end like Visual
Basic etc. then we can write code to validate what kind of
data the user can enter, save, update or delete. For
example, if we want the Name should not be greater than 20
characters, we can write code for this validation. If we
want that EmpID should be unique, we can write code for
this. If we want that Salary should always be a positive
number. I mean we can write code to completely manage how
the data should be delete/saved/updated in our database.

Now my questions is then why do we have to the double
work. Then where is the need to define the constraints
(column level or table level) in the database tables if
everything we can do in the Front-end development
language. Also, even we if we define the constraints in
the database tables still to check whether there is any
violation of those constraints we have do write code in
front-end application at least to trap the error to know
constraint failed?

[Ivan Demkovitch]

"good" question.

perhaps you don't even need sql server. Some earlier version of MS Access
will do.

DB design and programming has nothing to do with front-end programming.

I usually work hard on DB design and coding. Enforcing relationships, etc..
Then I can simply raise error to the client and do sloppy work on
client-side :-)

But seriously, when integrating different systems, creating different
front-ends, etc.. properly designed DB is
the best testing tool for front-end developers :-)



"sender" <user@domain.com> wrote in message
news:0eed01c34593$162e2da0$a001280a@phx.gbl...

> When we develop a package using front end like Visual
> Basic etc. then we can write code to validate what kind of
> data the user can enter, save, update or delete. For
> example, if we want the Name should not be greater than 20
> characters, we can write code for this validation. If we
> want that EmpID should be unique, we can write code for
> this. If we want that Salary should always be a positive
> number. I mean we can write code to completely manage how
> the data should be delete/saved/updated in our database.
>
> Now my questions is then why do we have to the double
> work. Then where is the need to define the constraints
> (column level or table level) in the database tables if
> everything we can do in the Front-end development
> language. Also, even we if we define the constraints in
> the database tables still to check whether there is any
> violation of those constraints we have do write code in
> front-end application at least to trap the error to know
> constraint failed?
>
>
>
>

[Andrew John]

Sender,

The validation at the front end overlaps the database, but I would dispute
the "completely" e.g. len(Name) < 20 might be checked / enforced twice,
but unique EmpID is a bit of a stretch.

The concept of any system (and I would include the front-end app and database
as seperate systems) checking it's inputs for errors is reasonable and prudent.

If your front-end app and database are so tightly ( and irrevokably ) coupled
that you consider them one system, then by all means only check/enforce integrity
in one location. Just don't expect a whole lot of sympathy when it fails.

Regards
AJ

"sender" <user@domain.com> wrote in message news:0eed01c34593$162e2da0$a001280a@phx.gbl...

> When we develop a package using front end like Visual
> Basic etc. then we can write code to validate what kind of
> data the user can enter, save, update or delete. For
> example, if we want the Name should not be greater than 20
> characters, we can write code for this validation. If we
> want that EmpID should be unique, we can write code for
> this. If we want that Salary should always be a positive
> number. I mean we can write code to completely manage how
> the data should be delete/saved/updated in our database.
>
> Now my questions is then why do we have to the double
> work. Then where is the need to define the constraints
> (column level or table level) in the database tables if
> everything we can do in the Front-end development
> language. Also, even we if we define the constraints in
> the database tables still to check whether there is any
> violation of those constraints we have do write code in
> front-end application at least to trap the error to know
> constraint failed?
>
>
>
>

[Robert Taylor]

I don't know about your app(s), but my databases have all
had to be integrated with multiple front ends, i.e., web,
VB, Access. etc. Unfortunately, this means even more than
double work, as I usually have to validate at the DB and
at the front end. But not every front end is under my
control, so I also set constraints at the DB level when
this is true.

This is only my opinion.

Robert

>-----Original Message-----
>When we develop a package using front end like Visual
>Basic etc. then we can write code to validate what kind

of

>data the user can enter, save, update or delete. For
>example, if we want the Name should not be greater than

20

>characters, we can write code for this validation. If we
>want that EmpID should be unique, we can write code for
>this. If we want that Salary should always be a positive
>number. I mean we can write code to completely manage how
>the data should be delete/saved/updated in our database.
>
>Now my questions is then why do we have to the double
>work. Then where is the need to define the constraints
>(column level or table level) in the database tables if
>everything we can do in the Front-end development
>language. Also, even we if we define the constraints in
>the database tables still to check whether there is any
>violation of those constraints we have do write code in
>front-end application at least to trap the error to know
>constraint failed?
>
>
>
>
>.
>