2005 Express OleDbConnection

  • Thread starter Thread starter Miro
  • Start date Start date
M

Miro

I think i have found my problem following an example ive searched for on the
net.

I am using vb.net 2005 express.

What I am looking for is a drag drop from the toolbar that is an
OleDbConnectionOleDbConnection and a OleDbDataAdapter so I can drag and drop
these on the from, and Connect them to an mdb file.

What I think I have come to, is that in 2005 Express you cannot do this.
You must code it manually all through code, such as
'Example: ===========
Dim daFileAdapter As New OleDb.OleDbDataAdapter()
daFileAdapter = New OleDb.OleDbDataAdapter("Select * From
Teacher", Connection )

Dim FileCommandBuilder As OleDb.OleDbCommandBuilder
FileCommandBuilder = New
OleDb.OleDbCommandBuilder(daFileAdapter)

Dim dtDataTable As New DataTable()
.... and so on
'==============

Can someone please let me know if the drag drop is possible in the VB 2005
Express ? - Or is it available in the Non Express Version ?

I hope this makes sence.

Thanks,

Miro
 
I may have just gotten one step closer.

I dragged the table from the dataset over to the form and I got some icons.
I think im on the right track!

Miro
 
Ok,

I know what my issue is ( how to ask it ) but dont know how to fix it.

As I understand it, by not adding a connection thru code, it adds it into
the "settings" as a connection string. This is a read only property and
this value cannot be changed at runtime.

My problem is that I dont know what the path is of the db file / dbfile
name/ or even the passsword ( if there is one ) until the program is
running and the user clicks a couple things.
So how can I have dynamic connection that I can choose to open and close.
It seems that the "settings" connectoin gets opened the second the form is
opend.
I would like to change the connection string and then continue on.

It seems that it is silly that vb stores the connection in a "setting" and
doesnt let you access / change the connection string.

I hope this makes sence.

Miro
 
Miro wrote:
As I understand it, by not adding a connection thru code, it adds it into
the "settings" as a connection string. This is a read only property and
this value cannot be changed at runtime.

My problem is that I dont know what the path is of the db file / dbfile
name/ or even the passsword ( if there is one ) until the program is
running and the user clicks a couple things.
So how can I have dynamic connection that I can choose to open and close.
It seems that the "settings" connectoin gets opened the second the form is
opend.
I would like to change the connection string and then continue on.
Click to expand...
<snip>

The connection is used by the DataAdapters, and is initially blank.
Only when the connection is needed for the first time is that the
DataAdapter loads it from the settings. This usually happens when you
perform a Fill for the first time.

I didn't try it, but the adapter's code seems to suggest that if you
assign the connection yourself, the new value will replace the
original. This must be done for each DataAdapter, and once for each
live instance of the DataSet (tipically, one per form).

HTH.

Regards,

Branco.
 
First off, let me say - Thanks for responding. I have been cracking my head
over this all day on and off.

I may not be fully understanding everything, but... let me try to explain a
couple things and my theory.

Here is an example of what I am trying to do ( and to do this without fully
doing it in code so i can drag drop ).

I have a file layout.
There are multiple files - with the same file layout in different folders.
( And i mean each have the same tables and fields - just different data )

The user double clicks on an option ( basically selects one one of the
files ) and Then I want to "change the connection string", and Open() the
connection.
Now, since the file "layouts" will always be the same I have a file layout I
specify in "Design" mode of my appliction so I can drag drop items into a
datagrid and such. But when the form is running, this db will either a) not
exist or b) is there but is irrelevant - its a blank db.

Currently - i do it by "code" and i dim a dataadapter with a stringVariable
as the connection that is open and continue on.

I must be missing something "big" or I dont see the big picture.
I would assume, the same way a Timer can be added to a from, a Connection
should be able to be added to a form.
This would have a property of "Open" "Close" and a path to the file and
such.
Simillarly an oledbConnection is added, and a dataAdapter.

So the form Loads...everything is off. You can have a command button and
that command button sets your "Connection" to Open() and then fills your
dataset and off you go.

Or is that too much dreaming.

Lets look at a simpler example.
You have Microsoft Word. Microsoft word can save multiple "word" documents
( or in my case mdb files ). It then can open any "word" document - from
anywhere. It can save / create new / delete ones on the fly.
That is why it seems silly that it wants to store a "connection string" and
make it read only in the "settings" portion of the application. By this
theory, Microsoft word would need to have hardcoded every possible document
name and location on your harddrive.

So am I missing something in my "logical thinking" of it being silly?
Im assuming my answer is not to drag drop the tables onto my forms, but I
have to do it all manually as I have started doing behind the sence inside
the code.

Thanks,

Miro
 
Ok,

For those of you who are interseted...im posting this cause ive spent hours
at this, went out and bought an ADO.net book and it was in there.

Here is what you do ( vb express 2005 ) to be able to use the objects in the
gui environment and a database connection that can be changed at runtime,
instead of it being stored in the application settings.

Right click on the TooBox Menu, and click on Choose Items

Add in the OleDbDataAdapter

Create a form
Add the OleDBDataAdapter.
Click on the little arrow in the top right of the oleDBDataAdapter and
"Configure Data Adapter", and also,
"Generate DataSet".

Create a DataGrid On your Form, and again with the little top right thingy,
choose your dataset.
-Add your columns

Now add a command button, and this code ( change the datasetname )'
===
If OleDbConnection1.State = ConnectionState.Open Then
OleDbConnection1.Close()
MyFirstDataSet1.Clear()
Debug.WriteLine("closed")
Else
OleDbConnection1.Open()
Debug.WriteLine("Fill")
OleDbDataAdapter1.Fill(MyFirstDataSet1)
Debug.WriteLine("Open")
End If
====


At this point the connection is not stored in teh Settings of the
Application, but it is stored on the form object.
By this being on the form object, you can add and use the Gui Environment to
add and delete columns on the form.
You can change your connection path / or whatever at runtime.

Great book...Microsoft ADO.Net 2.0 - Step By Step 2005 edition.
My 2003 vb.net book just doesnt cut it anymore.

I am happy now. Sorry for all the posts.

Miro
 
Which is exactly Branco told you in the first place, and also the same way
as you do it in all flavours of VB.NET (2002), VB.NET 2003 and VB.NET
(2005).

I think that we couldn't really understand why you couldn't 'get it' from
the start.

It might be all very well being able to drag-and-drop components on to a
form, but unless you have an understanding of what is happening 'under the
hood' then you really make a rod for your own back.

Wizards are really a 'one size - fits all' thing but thaey can only do what
they are configured to do. If you only know how to use the 'wizards' then
the moment that you need to do something that the wizard doesn't handle then
you are in trouble.
 
I have been coding without drag dropping.
So I have been recently trying to go the other route and trying to use the
gui editor ( drag drop ).

That is where the initial issue comes to play.
If you drag drop adding a dataset in the databrowser, it adds the connection
string into the Settings Portion of the application.
This Connection string cannot be modified at runtime.

By adding the data_adapter to the toolbar and adding it that way, gives you
the same control as doing it all thru code.

All part of the learning curve I guess,
I just wish the oleDataAdapter would have originally been in the toolbar.
If you search for "changing connection string at runtime" on the net, you
get some crazy solutions. None of which end up doing what I stated below.

Learn something every day i guess.

Miro
 
Back
Top