Visual Basic

Cliff Wellman8-Dec-03 2:43

8-Dec-03 2:43

As RageInTheMachine9532 said, a code sample would help us help you. Right now we don't have enough information.

meirav8-Dec-03 2:58

8-Dec-03 2:58

set db as database
set rec as recordset

open db=opendatabase("xx.mdb")
open rec=db.openrecordset("select * from xx",opendynaset)

I GOT ERROR AT LINE NUMBER 3

Cliff Wellman8-Dec-03 3:18

8-Dec-03 3:18

Well the syntax of your example is not correct but I think I know what you're trying to do.

The first thing that I'd do is try using the absolute path of the database and see if that works. Here is an example of the same code that I tried that worked.

    <br />
Dim db As Database<br />
Dim rs As Recordset<br />
  <br />
' open the database in the application directory<br />
Set db = OpenDatabase(App.Path & "\mydata.mdb")<br />
Set rs = db.OpenRecordset("SELECT * FROM MYTABLE")<br />

The only other thing that I'd recommend is that you use ADO vs. DAO.

meirav8-Dec-03 4:42

8-Dec-03 4:42

i tried to do it but i get the same massege
any connection to the projet refrenses, i choose(microsoft dao 3.6)?

Dave Kreskowiak8-Dec-03 4:57

8-Dec-03 4:57

Then you might want to try hard coding the entire path to the database in your OpenDatabase statement because it looks like OpenDatabase can't find your filename in the default path or the path your project is running from.

Dim db As Database
Dim rs As Recordset

' open the database from exactly where I say it is
Set db = OpenDatabase("C:\FullPath\ToMyDatabase\mydata.mdb")
Set rs = db.OpenRecordset("SELECT * FROM MYTABLE")

and SERIOUSLY consider moving your code to ADO instead of DAO. DAO seems to be a dead technology.
If your using VB6, you can start here[^] to learn about ADO.
If your using VB.NET, you might want to start here[^].

RageInTheMachine9532

Cliff Wellman8-Dec-03 4:57

8-Dec-03 4:57

In Project References try using:
"Microsoft ActiveX Database Object 2.7 Library."

If you don't have the 2.7 library, you should have either 2.0, 2.1, 2.5, or 2.6. Use one of them.

I was looking in the VB documentation and for DAO it says that the OpenDatabase statement is depricated and that you should use the DBEngine object to open a database. So if you must use DAO, then try checking out the documentation on the DBEngine object.

By the way, I was able to use DAO to access my database. So maybe you have some other configuration problem.

meirav8-Dec-03 8:15

8-Dec-03 8:15

I am using access 2003. is there any special configuration for this version that you know about that i should try?

Cliff Wellman8-Dec-03 8:28

8-Dec-03 8:28

Are you getting an error number?

I tried to open a file that didn't exist and I got a run time erro #3024. Is that what you get? Or do you get some other number error number?

Regarding Access 2003, I'm not aware of any configuration stuff that would affect a VB program.

meirav8-Dec-03 9:18

8-Dec-03 9:18

Yes, this is the error number i get. but the exist.

Cliff Wellman8-Dec-03 9:28

Shared members raising events

8-Dec-03 9:28

I'm grasping at straws...but have you tried opening up another database file. Maybe create a database with one table and try to access that.

OR

Maybe it's a sharing violation. In the past I've had trouble opening a database if I had it open in MS-Access, especially if it's open exclusively by MS-Access.

cnurse5-Dec-03 21:58

Re: Shared members raising events

5-Dec-03 21:58

This seems a real tricky one.

I want a class which is a single instance. So what I did was make all its members shared and they in turn are accessed by property gets/sets as you would expect. I then want a shared timer, so no matter how many other objects have a reference to my "singleton" class they all receive a polled event which emanates from the one timer.

I want a timer in the singleton class that polls all interested parties at one tick every 100 ms. Problem is because the timer is shared...

Shared mTimer as New Timer

The event that the Timer class raises is shared...

Shared Sub mTimer_Tick...

If I try and do this...

Shared Sub mTimer_Tick...
RaiseEvent MyTimerEvent
end sub

I have to write....

Shared event MyTimerEvent

But then in my object which utilises this class....

Dim WithEvents mObject as MySingletonObject

This fails because it says there are no events that can be raised on MySingletonObject which is bull. So this is something to do with have shared members that raise events that you in turn want to pass onto to a whole heap of other objects, and I can't find a way to do it. If I was to fall back to C++, I'd start sending Window messages, like the fix for having a timer on one thread which polls a window on another thread to say the timer has fired, remember that one!

Ah well, any corrections to my technique will cause tears and tantrums, but I will try and listen hahahaha

Thx!

Nursey

cnurse6-Dec-03 22:47

6-Dec-03 22:47

Dear all,

I've now seen the error of my ways and produced a more elegant way, and adopted a more technically correct approach from an OO point of view.

I have a polling class and a polled object interface which people can implement. They register their objects with the "poller" and it polls all registered object periodically, so I have a single timer object which can trigger events in many objects which I think gives me basically limitless resource, rather than having loads of timers running. This lets me do things like blinking buttons, if you're interested.

Anyway, it will all be included in the next release of my XP buttons and docking containers release.

Thanks anyway.

Nursey

Bit shifting in VB

cnurse5-Dec-03 18:59

5-Dec-03 18:59

Can I use bit shifting operators in VB. According to MSDN I can. But...my msdn library is 2003 and my VB is 2002! Do I have to import something because I see erros when I try a = B >> 2. I am using VB 2002.

Thanks you lot!

Nursey

Dave Kreskowiak6-Dec-03 4:58

6-Dec-03 4:58

The bit shift operators are new to 2003. They don't exist in 2002...
Sorry!

RageInTheMachine9532

cnurse6-Dec-03 22:54

6-Dec-03 22:54

Hey Rage,

I thought as much, presumably they are in C# so really I could just knock up a quick C# object which offers bit shifting and byte extraction from 32-bit ints, the stuff we take for granted in C++.

As a feeler, how long has it taken people to get to grips with C# if you know C++, or VB for example?

Just another language is what I say, and they should all be learned if possible, it helps you to think outside the box.

Chris.

Nursey

Dave Kreskowiak7-Dec-03 5:39

7-Dec-03 5:39

And your right my friend! This is what learning all those different languages is all about! I prefer VB for the bulk of my code just because it's fast to write up. But I also write components in C# and C++, and for the real down and dirty with API's, NetWare, and libraries, in use C++.

It didn't take very long at all to get used to C#, having a background in both VB and C++, it was a snap to learn. It just took a couple weeks to get used to the hybrid syntax! Big Grin | :-D

In all, I think I have my hands in something like 14 different languages. I'm by no means a master of all of them, but the concepts are the same amongst them all. But you're right! The more you know, the better off you are!

RageInTheMachine9532

cnurse7-Dec-03 13:45

7-Dec-03 13:45

Well, as soon as I have put some polish on this current control library I'll dive into C#. I have a feeling the hybrid syntax will be pretty intuitive. I just have to remember to keep putting the ";" in the right places again!

Have you used any free tracing tools that help you to dig out strange bugs which are hard to track down at design time? I was getting "Null reference exception..." and I couldn't pinpoint the line which it was at until I put some message boxes in. It seems at design time code gets run which you can't step through. I remember running two copies of VB6 to debug controls at design time. Presumably that's still an option?

Ta.

Nursey

Dave Kreskowiak7-Dec-03 14:40

7-Dec-03 14:40

Yep, you can debug design-time code just about the same way you could under VB6. Microsoft was kind enough to supply a sample of it here[^].

RageInTheMachine9532

Ian Darling7-Dec-03 2:43

Ian Darling

7-Dec-03 2:43

The previous poster is correct - the shifting operators are 2003 only.

However, if you have an integer value you can mimic some of the shifting by dividing or multiplying by two, although this is far from perfect and may cause overflow errors and suchlike. You might also find that you can bit mask, and created the shifted up or down value by adding or subtracting the relevant powers of 2 to an initial zero value.

You could also create a lookup table of shifts if you don't mind the memory overhead, but this would be fast and simple (note this is only really practical for small bitfields, of size 8 bits or there abouts (an array 256 Bytes each way) - 32 bits woud be right out due to needing 4 gig of memory for each Big Grin | :-D

)

Or upgrade your project to 2003 Smile | :)

--
Ian Darling
"The moral of the story is that with a contrived example, you can prove anything." - Joel Spolsky

cnurse7-Dec-03 4:22

VB.Net WS_EX_LAYERED Forms

7-Dec-03 4:22

Having put your 4 Gig of memory method to the test I seem to have scratched the area of my hard disk, right around the place where the swap file seems to go Wink | ;-)

I am gonna go the C# route just to have a little utility function until my 2003 hits the front door carpet. I was using the div mul method of shifting up until now though and who cares if its 4 nano seconds slower than the C++ like bit shifts!

Ah well, all I have to do now is wait for the garbage collector to give me my 4 gig back hahaha 8-)

See Yah!

Nursey

andrew|5-Dec-03 4:32

andrew|

5-Dec-03 4:32

Hello! Im new to these forums so please forgive me if I have posted in the wrong section for this.

Using winforms under vb.net, how does one set the GWL_EXSTYLE to include WS_EX_LAYERED? I need to set this
flag so that I may use UpdateLayeredWindow on the form. This is what I am using :

Dim lStyle As Long = GetWindowLong(Me.Handle.ToInt32, GWL_EXSTYLE)
lStyle = lStyle And WS_EX_LAYERED
Dim retval As Long = SetWindowLong(Me.Handle.ToInt32, GWL_EXSTYLE, lStyle)

I tried it after a .Show() call and in the _Load event as well.

Someone, please enlighten me! This is holding up my project atm. Thanks!

Edited by - andrew_ on 12/4/2003 8:09:57 PM

cnurse5-Dec-03 18:56

5-Dec-03 18:56

Andrew,

I sincerely hope this example, which I found for you, helps out...

Using Layered Windows

To have a dialog box come up as a translucent window, first create the dialog as usual. Then, on WM_INITDIALOG, set the layered bit of the window's extended style and call SetLayeredWindowAttributes with the desired alpha value. The code might look like this:

// Set WS_EX_LAYERED on this window
SetWindowLong(hwnd,
GWL_EXSTYLE,
GetWindowLong(hwnd, GWL_EXSTYLE) | WS_EX_LAYERED);

// Make this window 70% alpha
SetLayeredWindowAttributes(hwnd, 0, (255 * 70) / 100, LWA_ALPHA);
Note that the third parameter of SetLayeredWindowAttributes is a value that ranges from 0 to 255, with 0 making the window completely transparent and 255 making it completely opaque. This parameter mimics the more versatile BLENDFUNCTION of the AlphaBlend function.

To make this window completely opaque again, remove the WS_EX_LAYERED bit by calling SetWindowLong and then ask the window to repaint. Removing the bit is desired to let the system know that it can free up some memory associated with layering and redirection. The code might look like this:

// Remove WS_EX_LAYERED from this window styles
SetWindowLong(hwnd,
GWL_EXSTYLE,
GetWindowLong(hwnd, GWL_EXSTYLE) & ~WS_EX_LAYERED);

// Ask the window and its children to repaint
RedrawWindow(hwnd,
NULL,
NULL,
RDW_ERASE | RDW_INVALIDATE | RDW_FRAME | RDW_ALLCHILDREN);

Nursey

andrew|5-Dec-03 21:24

andrew|

5-Dec-03 21:24

Nursey, thanks for trying address the issue at hand here.

My main objective is to draw to an offscreen DC and use UpdateLayeredWindow to render the form. Being VB.NET Winforms, I am not quite sure how one goes about handling the WM_CREATE, or WM_INITDIALOG messages. If this were VB6 or below I would have no problem with this.

The reason why I thought it would be worthwhile to pose the question is because I had checked the winform with spy++ and the WS_EX_LAYERED exstyle was not listed for the window.

If there is a setting or a way to assert the WX_EX_LAYERED exstyle to a winform without calling SetWindowLong (Which has no effect on the winform at all) please do let me know!

Thanks!

Dave Kreskowiak6-Dec-03 4:57

6-Dec-03 4:57

Just for learning purposes ... What are you trying to do with the layered window? What is the goal of rendering the window offscreen?

SetWindowLong is the only way your going to set WS_EX_LAYERED, BUT what I noticed in your code is that your ANDing the value in. You must OR the value in to get it to work, at least in the examples I've found (see here[^])

RageInTheMachine9532