parent child grandchild grids

[Richard Fagen]

Hi,

I wondering if someone can explain the best way to show three datagrids
in a parent/child/grandchild relationship?

For example:
Take a simple form with 3 datagrids - the top for the customers, the
middle for the orders, and the bottom for the items of the order.

I'd like to know the best why to update the grids so that when the user
changes the current row in the customers' grid, only that customer's
orders are displayed in the middle orders grid. At the same time, I'd
like the bottom items' grid to display only the rows belonging to the
currently selected order in the middle grid.

I've been doing this for years in other languages (mostly DOS based
xBase languages) but I am new to doing this in VB.

Can anyone get me started?

Richard

[Cor Ligthert]

Richard,

There is no best way.

I myself go mostly for the situation when it are comboboxes to create
dependable dataviews.

This I did not with a datagrid however it should be possible when you use
the currencymanager (I never did it this way)

Datagrid 1 is a full datagrid of all

Datagrid 2 is a datagrid, that has a dataview with rowfilter depending on a
column on the current position of datagrid1 (you need the currencymanager
for that, that is not about money what a lot of people think at the start)

http://msdn.microsoft.com/library/de...classtopic.asp

Datagrid 3 is a datagrid, that has the same based on Datagrid2

It needs to much code (sample datatables) to make a simple sample for this.

You can however as well go for the datarelation way.

http://msdn.microsoft.com/library/de...tionstopic.asp

As I said before I never did this kind of things with 3 deep except with the
combobox and than I have again another approach.

I hope thst this gives some ideas.

Cor

[Richard Fagen]

Hi Cor,

I have started experimenting with the CurrencyManager and the DataView
and they seem to be exactly what I need.

My question is where should I declare them?

I would like to be able to access Dataviews and rowfilters from an event
and I don't know who to give them proper scope.

I tried to declare them at the top of the form but I was having trouble
with the data adapters.

Where is the best place to declare the following (top of form, code
module, form load event?)
- sqlconnections
- data adapters
- data sets
- relations
- dataviews

You have definitely given me many ideas to try out, thanks!

Richard

Cor Ligthert wrote:

Richard,

There is no best way.

I myself go mostly for the situation when it are comboboxes to create
dependable dataviews.

This I did not with a datagrid however it should be possible when you use
the currencymanager (I never did it this way)

Datagrid 1 is a full datagrid of all

Datagrid 2 is a datagrid, that has a dataview with rowfilter depending on a
column on the current position of datagrid1 (you need the currencymanager
for that, that is not about money what a lot of people think at the start)

http://msdn.microsoft.com/library/de...classtopic.asp

Datagrid 3 is a datagrid, that has the same based on Datagrid2

It needs to much code (sample datatables) to make a simple sample for this.

You can however as well go for the datarelation way.

http://msdn.microsoft.com/library/de...tionstopic.asp

As I said before I never did this kind of things with 3 deep except with the
combobox and than I have again another approach.

I hope thst this gives some ideas.

Cor

[Cor Ligthert]

Richard,

I would not worry to much at this moment about what you ask now.

datagrid1.datasource = dataview1

than
directcast(datagrid1.datasource,dataview).table (gives you your original
table
than
directcast(datagrid1.datasource,dataview) gives you your used dataview
(depend of you instanced it with new, otherwise is that the
datatable.defaultview

However don't worry first try to understand those other things in my opinion
and make your program running. Optimizing comes when you understand what you
are doing.

The rule is that when you can declare/instance something as low as possible
in a method you would have to do that. (Gives beside better reading a better
performance of the GC).

What gives:
(Load event) is as every method
Top of form is global for the class
Module is global for your application.

As exacmple
Not
Dim i as integer,
for i = 0 to end
however
for i as integer = 0 to end

And only when this is not possible than every time a level higher (by
instance in this sample when you exit the for loop and need that "i" because
that was the last one)

I hope this helps,

Cor

[Richard Fagen]

Hi Cor,

Thanks for your help. I almost got it the way I want. I need to do
more testing.
Richard

p.s. thanks for the idea about directcast, I never even heard of that
command :)

Cor Ligthert wrote:

Richard,

I would not worry to much at this moment about what you ask now.

datagrid1.datasource = dataview1

than
directcast(datagrid1.datasource,dataview).table (gives you your original
table
than
directcast(datagrid1.datasource,dataview) gives you your used dataview
(depend of you instanced it with new, otherwise is that the
datatable.defaultview

However don't worry first try to understand those other things in my opinion
and make your program running. Optimizing comes when you understand what you
are doing.

The rule is that when you can declare/instance something as low as possible
in a method you would have to do that. (Gives beside better reading a better
performance of the GC).

What gives:
(Load event) is as every method
Top of form is global for the class
Module is global for your application.

As exacmple
Not
Dim i as integer,
for i = 0 to end
however
for i as integer = 0 to end

And only when this is not possible than every time a level higher (by
instance in this sample when you exit the for loop and need that "i" because
that was the last one)

I hope this helps,

Cor