SQL Assist - Android Software Development

I'm usually pretty good with my SQL statements, but I'm stuck on something and just need to let someone else see it. Here's a sample of the data:
(id | name | time in text | time in milliseconds | lap number)
439|DAVID|0:03.30|3030|1
440|CHRIS|0:04.46|4610|1
441|DAVID|0:05.53|5394|2
442|CHRIS|0:06.63|6321|2
443|CHRIS|0:03.37|3716|3
444|DAVID|0:07.72|7277|3
This is how I need it ordered:
439|DAVID|0:03.30|3030|1
441|DAVID|0:05.53|5394|2
444|DAVID|0:07.72|7277|3
440|CHRIS|0:04.46|4610|1
442|CHRIS|0:06.63|6321|2
443|CHRIS|0:03.37|3716|3
It's based on the minimum value in column 3 (time in milliseconds) and then all rows for that person. Now if on lap 4 Chris has a 2900 millisecond time, HIS laps would be first and then David's.
Note that there could be 1 to x number of people; they're created dynamically at runtime.
I'm just drawing a zero on this LOL
Tia,
Roots

I'm not sure what you're asking. Just an ORDER BY term maybe?
"SELECT ... ORDER BY name,time"

I wish it was that easy. Think of it as a qualifying lap timer for racers. Say 2 guys from a team are running on a track and do maybe 10 laps each.
At the END of each lap, times are recorded and stored as shown in first dataset above.
I need to get the FASTEST lap time of the 2 drivers and get the rest of THAT person's laps....hopefully in one statement. Then the same for driver #2 (or more)

Can't you select the min(laptime) for each person as a calculated field and use that along with the lapnumber to order by?
I don't know which dbms you're using, but this works with ms-sql-server :
assuming your table looks something like this:
create table #tbl (id int, nom char(5), timestr char(7), timems int, lapnum int)
then a query like this would do it:
select id, nom, timestr, timems, lapnum
from #tbl
order by (select min(timems) from #tbl as tblsub where tblsub.nom = #tbl.nom), lapnum

how big is the dataset?

Data set is small..maybe max rows will hit 30.
And for the post above, off the top of my head I don't think you can "Order By" an aggregate such as you have it written...but I'll try it tomorrow..done coding for the day LOL

Add the minimum seconds as a column with a subselect. I think this format is correct.
Select id, name, time, seconds, lap, (select min(seconds) from mytable where name = a.name) as min_seconds
from mytable a
order by min_seconds, name, lap;
________________________________
http://ron-droid.blogspot.com

I tired it...no joy
sqlite> select nameShort, lapTimeMilli, (select min(lapTimeMilli) from session where nameShort = a.nameShort) as min_seconds from session a;
DAVID|3030|3030
CHRIS|4610|3716
DAVID|5394|3030
CHRIS|6321|3716
CHRIS|3716|3716
DAVID|7277|3030
I think as soon as I do "min(lapTimeMilli)" it gets ONE and only ONE value...the minimum lap time. I think I'm going to have to grab that min lap time and then do another select to get the rest of the rows for that fastest lap person.
Then, somehow, get the rest of the racers and lap times in order (gonna need to pass List of racer names). I still think there's a way to do it with one statement...inner/outer join, sub selects, UNION...something! LOL
I guess if the number of rows is going to be small, in can Insert into session1, session2, the SAME data...get min lap time and then UNION to get the other rows. Still leaves problem of remaining drivers...ugh

messing around this morning, i got the following...close, but David needs to come first LOL
sqlite> select nameShort, min(lapTimeMilli) from session union select nameShort, lapTimeMilli from session;
CHRIS|3716
CHRIS|4610
CHRIS|6321
DAVID|3030
DAVID|5394
DAVID|7277

I'm not familiar with sqlite syntax, but if you can't order by a subquery, can you join to a subquery and order by a field from the subquery?
like this:
select #tbl.id, #tbl.nom, #tbl.timestr, #tbl.timems, #tbl.lapnum, subq.mintime
from #tbl
inner join
(
select nom, min(timems) as mintime from #tbl group by nom
) as subq
on #tbl.nom = subq.nom
order by subq.mintime, lapnum

Rootstonian said:
Data set is small..maybe max rows will hit 30.
And for the post above, off the top of my head I don't think you can "Order By" an aggregate such as you have it written...but I'll try it tomorrow..done coding for the day LOL
Click to expand...
Click to collapse
You obviously didn't try it! I just downloaded sqlite and tried it and it works just fine.
Code:
create table tbl (id int, nom char(5), timestr char(7), timems int, lapnum int);
insert into tbl(id, nom, timestr, timems, lapnum)
select 439,'DAVID','0:03.30',3030,1
union all select 440,'CHRIS','0:04.46',4610,1
union all select 441,'DAVID','0:05.53',5394,2
union all select 442,'CHRIS','0:06.63',6321,2
union all select 443,'CHRIS','0:03.37',3716,3
union all select 444,'DAVID','0:07.72',7277,3;
select id, nom, timestr, timems, lapnum
from tbl
order by (select min(timems) from tbl tblsub where tblsub.nom = tbl.nom), lapnum;
returns:
439|DAVID|0:03.30|3030|1
441|DAVID|0:05.53|5394|2
444|DAVID|0:07.72|7277|3
440|CHRIS|0:04.46|4610|1
442|CHRIS|0:06.63|6321|2
443|CHRIS|0:03.37|3716|3
drop table tbl;

Rootstonian said:
I tired it...no joy
sqlite> select nameShort, lapTimeMilli, (select min(lapTimeMilli) from session where nameShort = a.nameShort) as min_seconds from session a;
Click to expand...
Click to collapse
If that is your complete statement based on my example, you forgot the order by clause.
________________________________
http://ron-droid.blogspot.com

Rootstonian said:
Data set is small..maybe max rows will hit 30.
And for the post above, off the top of my head I don't think you can "Order By" an aggregate such as you have it written...but I'll try it tomorrow..done coding for the day LOL
Click to expand...
Click to collapse
If you dont need to scale much beyond this then you could just do all this in Java instead of SQL. That's a tiny amount of data, easily loaded into memory and iterated through. Then you can sift it, sort it, prod it, poke it, whatever

alostpacket said:
If you dont need to scale much beyond this then you could just do all this in Java instead of SQL. That's a tiny amount of data, easily loaded into memory and iterated through. Then you can sift it, sort it, prod it, poke it, whatever
Click to expand...
Click to collapse
But then he will get an F on his SQL homework if he does it all in Java

peegee99 said:
But then he will get an F on his SQL homework if he does it all in Java
Click to expand...
Click to collapse
haha Ah good to wake up to a good joke.

This thread looks like it belongs more in SO

peegee99 said:
But then he will get an F on his SQL homework if he does it all in Java
Click to expand...
Click to collapse
Not homework, for a program. And yes, your answer is correct. I'm sorry I didn't get back to this, but I'm currently working on 3 projects
I got this SQL from my retired DBA friend...similar to yours
Code:
select session.nameShort,
session.lapTime,
session.lapTimeMilli,
subquery.mintime
from session
inner join
(select nameShort,
min(lapTimeMilli) as mintime
from session
group by nameShort) as subquery
on session.nameShort = subquery.nameShort
order by subquery.mintime,
session.lapTimeMilli;
Thank you everyone for your help, I appreciate more than you know...I was really stuck on this!
Roots

I'm curious, why store the lap times as two fields, string and int?
It would probably be better to have one field with a long for the total lap time in milliseconds, then convert to minutes/secs/ms in the UI. That would also make localization easier, if certain countries want a different format for the time.

jgittins said:
I'm curious, why store the lap times as two fields, string and int?
It would probably be better to have one field with a long for the total lap time in milliseconds, then convert to minutes/secs/ms in the UI. That would also make localization easier, if certain countries want a different format for the time.
Click to expand...
Click to collapse
I'm not sure why I did that LOL It's not a big dataset, but yeah, to be most "code efficient" I will remove the string column and convert when I pull the data.

Related

Simple Programming Question embedded VC++

I'm currently doing some programs myself with the free MS embedded VC++.. and I'm finding it comfortable to do a simple dialog-based programs for PPC. I think I can have most of the background code going, and I've just got the GUI .. alright.
Now the question, how do I do a copy/paste to/from clipboard? I had most of the stuff done using the included MFC Wizard. I can get and send data to/from an EditBox (TextBox, whatever you call it). However, the click-hold thing on PPC doesn't seems to work on my EditBox, and hence I'm thinking what's needed to enable a simple Copy/Paste on an EditBox.
Currently, I'm using the simple
Code:
m_editBox = _T("the message I want to show");
UpdateData(FALSE); //send it to the EditBox
Any guide from here would be appreciated. However, I'm thinking there may not be an easy way to do that, hence I've also tried adding a 'Copy' and 'Paste' button to do the job, but I've tried things like
Code:
SetClipboardData(x, x)
GetClipboardData(x)
None works.
I have also tried
Code:
COleDataObject DataObject;
and with the handle etc etc .. but I can't seems to find this COleDataObject , is that in some other environment (e.g. not PPC env)?
Help
Fast solution:
http://www.pocketpcdn.com/articles/sip.html
(this shows/hides sip on get/lost focus in edit controls and add the context menu too)
and this is a simple example how to copy datas into clipboard
if(OpenClipboard(NULL))
{
EmptyClipboard();
HLOCAL clipbuffer = LocalAlloc(0, 100);
wcscpy((WCHAR*) clipbuffer, (WCHAR*) (vtNumber.bstrVal));
SetClipboardData(CF_UNICODETEXT, clipbuffer);
CloseClipboard();
free(szMsg);
LocalFree(clipbuffer);
}
I hope this help u
bye
Thanks for your respond.. things work.. a bit
Code:
//put a test char
char *test;
test = (char*) malloc(100);
strcpy(test, "blah blah blah");
//codes you've given
if(OpenClipboard()) //OpenClipboard(NULL) gives me error
{
EmptyClipboard();
HLOCAL clipbuffer = LocalAlloc(0, 100);
wcscpy((WCHAR*) clipbuffer, (WCHAR*) test);
SetClipboardData(CF_UNICODETEXT, clipbuffer);
CloseClipboard();
//free(szMsg); //not sure what 'szMsg' is
LocalFree(clipbuffer);
}
Things somewhat works. I'm not really sure which part I've got wrong. I'm suspecting some memory allocation is giving me problems. The thing is, if I were to use 'CF_UNICODETEXT' on the 'SetClipboardData(x,x)' line, I get something to paste on other programs (PPC Notes). BUT, the thing pasted is some funny stuff (e.g. letters that cannot be rendered, hence I get the little squares). If I were to use 'CF_TEXT', I don't seems to able to send my stuff to the clipboard or it made it invalid for (PPC Notes) pasting (e.g. I'm not able to paste it in PPC Notes).
Thanks.
BTW, if you are in the mood, can you give me a Paste function as well. Thanks a bunch.
Hi hanmin.
Odd I didn't notice this thread sooner.
Any way if you still having problems with this code here is the solution:
You are working with char and strcpy so your text is in ASCII (each letter one byte).
But you are calling SetClipboardData with CF_UNICODETEXT so it expects WCHAR (UNICODE) where each letter is two bytes.
The strange letters are the result of two consecutive bytes being interpreted as a single letter (probably lends you in Chinese or Japanese region of the Unicode table)
Windows mobile doesn't usually work with ASCII so the text you get from the edit box will already be in Unicode and won't give you any trouble.
The code should look like this:
Code:
//put a test char
CString test; //since you are working with MFC save your self the trouble of memory allocation
test = L"The text I want on clipboard"; //The L makes the string Unicode
//codes you've given
if(OpenClipboard()) //OpenClipboard(NULL) gives me error
{
EmptyClipboard();
//not sure why you need to copy it again, but here goes:
HLOCAL clipbuffer = LocalAlloc(0, test.GetLength() * 2); //remember: every letter 2 bytes long!
wcscpy((WCHAR*) clipbuffer, (WCHAR*)(LPCTSTR)test); //LPCTSTR is an overloaded operator for CString
SetClipboardData(CF_UNICODETEXT, clipbuffer);
CloseClipboard();
//szMsg probably belongs to some larger application and is irrelevant
LocalFree(clipbuffer);
}
I never used the clipboard APIs my self so I can't guide you farther but this code should work.
Hope this helps.
Wooo hooo.. Thanks levenum. I'm back on business!
You code works wonderfully.. just the final code "LocalFree(clipbuffer);" seems to cause problems. Without that, it works. I'm not sure if it will cause a memory leak.. but that's not much of my concern now
Now my Paste also works, and it seems that the magic code is the "LPCTSTR", which I have NO idea what it is (I'm more of a pure C person and.. a Java person ) Thanks again.
Glad I could help.
I am working from Ubuntu right know (Linux distro in case you didn't know) so I do not have access to my off-line MSDN files, but I recommend you check out the documentation for SetClipboardData.
It is possible it releases the memory it self so when you call LocalFree the handle is no longer valid.
That could also be the reason why you need to allocate memory instead of passing it the string directly.
As for LPCTSTR it is simple and not C++ related:
#define const* WCHAR LPCTSTR
Its M$ way of saying Long Pointer to Constant STRing
T changes meaning based on what you are working with:
If you work with ASCII TCHAR is char
If you work with Unicode TCHAR is WCHAR
Basically these are just all redefinitions of variable types so you can distinguish what they are used for.
In C++ you can overload operators. For example you can have a function which changes the way ++ works with certain types of variables.
In our case CString class has a function which determines what happens when you try to cast (convert) it to a pointer to string.
Thats all the "magi" code.
Good luck with your app.
Small update:
Since I had to go in to XP anyway (to change PDAMobiz ROM which kept hanging at random and didn't let me use BT to latest PDAViet which for now seem very good) I took a quick peek at the help files.
Here is why you should not release the memory:
After SetClipboardData is called, the system owns the object identified by the hMem parameter. The application can read the data, but must not free the handle or leave it locked. If the hMem parameter identifies a memory object, the object must have been allocated using the LocalAlloc function
Click to expand...
Click to collapse
levenum, thanks. You've got me almost there. There are several stuff I need to polish up though. Attach is a pre-mature version of what I wanted to do. There are several issues (including the fact that, only the 4 characters of the password are effectively used, which can be easily fix, I think. Just need to find the bug and squash it) that I like to polish up. They are sorted in order of importance (to me):
[1] Keyboard (SIP) pop up.
For this, I digged around and got to know that the function
"SHSipPreference( HWND, SIP_UP)" is the one to used. However, it never did what it suppose to do. I have had it put inside the "OnSetfocusConfirmPasswordEdit()" of the edit box, which should be called when it is set focus. I suspect that is I haven't set the HWND correctly. I have tried "NULL" and also tried using the "CWnd* pParent" from my dialog constructor (generated code my MFC Wizard). None of them worked.
[2] Editbox focusing.
For some reason, the focus on my main-dialog is correct on the editbox of the 'message'. However, on the dialog which is to confirm the password (which I called using
Code:
CConfirmPasswordDlg confirmPasswordDlg;
int nResponse = confirmPasswordDlg.DoModal();
is focusing on the 'Ok' button. What I like it to do is to focus on the 'confirmPasswordEdit' box, and it ought to automatically pop up the keyboard (SIP).
[3]Reduced size pop up dialog
I was trying to make the 2nd confirm password dialog smaller, something like a pop up in the PPC rather than something that take up the whole screen without much contents in it. How would you go about doing that? Is it not possible in PPC? E.g, if you were to use Total Commander, and start copying files around, they do have a pop up that does take up the entire screen. I'm suspecting I shouldn't do a "confirmPasswordDlg.DoModal()", and should some what do something myself. I have tried, SetVisible(1) thing, but that doesn't work. Or it shouldn't meant to work because my 1st screen is a dialog screen?
[4]Timer?
I would like to have a function of which after a certain period of idle time, it will clear off the clipboard and close itself. How would I go about doing this? Some sort of background thread thing?
Anyone can shine a light on my issues above? On MS-embedded Visual C++ (free), with Pocket PC 2003 SDK (free)
Attached the Blender-XXTea edition
Works on PPC2005 and WM5 (should work on WM6)
Does not require .NET framework
VERY small (54K)
hanmin said:
[2] Editbox focusing.
For some reason, the focus on my main-dialog is correct on the editbox of the 'message'. However, on the dialog which is to confirm the password (which I called using
Code:
CConfirmPasswordDlg confirmPasswordDlg;
int nResponse = confirmPasswordDlg.DoModal();
is focusing on the 'Ok' button. What I like it to do is to focus on the 'confirmPasswordEdit' box, and it ought to automatically pop up the keyboard (SIP).
Click to expand...
Click to collapse
In your CConfirmPasswordDlg::OnInitDialog handler, call GetDlgItem(confirmPasswordEdit).SetFocus() and return FALSE. That should handle the focus and possibly the SIP popup.
3waygeek said:
In your CConfirmPasswordDlg::OnInitDialog handler, call GetDlgItem(confirmPasswordEdit).SetFocus() and return FALSE. That should handle the focus and possibly the SIP popup.
Click to expand...
Click to collapse
HEY! The focus works! The working code is
Code:
((CWnd*) CConfirmPasswordDlg::GetDlgItem(IDC_CONFIRM_PASSWORD_EDIT))->SetFocus();
BTW, I'm wondering, whats the effect of a return TRUE/FALSE on a 'OnInitDialog()'?
Anyway, the keyboard pop up is still not working. I'm using the command
Code:
void CConfirmPasswordDlg::OnSetfocusConfirmPasswordEdit() {
SHSipPreference( (HWND)g_pParent, SIP_UP);//
}
which I suspect the 'g_pParent' is NULL. If it is NULL, would it work?
Ok, I haven't used MFC for a while and almost not at all on PPC but I will give this a shot:
1) MFC forces dialogs to be full-screen. Here is a detailed explanation on how to change that. Note that for some reason this will work only once if you use the same variable (object) to create the dialog several times.
If you use a local variable in say a button handler thats not a problem because the object is destroyed when you exit the function.
2) There is a simple SetTimer API. You can give it a window handle and then add an OnTimer message handler to that window. Or you could give it a separate function which will be called (say TimerProc). In that case you can give it NULL as window handle.
Note that CWnd objects have a member function with the same name (SetTimer) which sets the timer with that window handle (so that window will receive WM_TIMER message). If you want the raw API call ::SetTimer.
Also note that the timer will continue to send messages / call your special function every x milliseconds until you call KillTimer.
3) I am not sure what the problem with the SIP is. CWnd and derived classes like CDialog have a function called GetSafeHwnd (or GetSafeHandle, I don't remember exact name). Try passing that to SHSipPreference.
If that does not work here is an article with an alternate solution.
WOHO!! Everything works NOW!!.. MUAHAHHAHA.. wait til you see my release version
Non maximized windows works using the code suggested at the page. Although I still do not understand where the heck this '.m_bFullScreen' property came from. It is not anywhere obvious to be seen.
Code:
CNfsDlg dlg;
dlg.m_bFullScreen = FALSE;
dlg.DoModal();
Timer works using the
Code:
xx{
//your code...
CBlenderDlg::SetTimer(1, 5000, 0); //event 1, 5 seconds, something
//your code...
}
void CBlenderDlg::OnTimer(UINT nIDEvent){
//do something here for the timer
}
although somehow, the OnTimer() only works if I went to the MFC class wizard to add the WM_TIMER function. Doesn't work when I add in the OnTimer() myself. Must be something else that I've missed. Anyway.
Keyboard issue solved using
Code:
SHSipPreference( CBlenderDlg::GetSafeHwnd(), SIP_UP);
Glad its working out for you.
Couple of comments:
1) Somewhere at the top of the cpp file, if I am not mistaking there is something called a message map. It's a bunch of macros that lets MFC know what window messages it handles. An entry there is what was missing when you added the function manually.
2) m_bFullScreen is just another among many undocumented features. M$ likes to keep developers in the dark. For instance WM 2003 and up have an API called SHLoadImage which can load bmp, gif, jpg and some other formats and return HBITMAP which all the usual GDI functions use.
This API was undocumented until WM 5 came out and even then they said it only works for gif...
hanmin said:
BTW, I'm wondering, whats the effect of a return TRUE/FALSE on a 'OnInitDialog()'?
Click to expand...
Click to collapse
The return value indicates whether or not the standard dialog handler (which calls your OnInitDialog) should handle setting the focus. As a rule, OnInitDialog should return TRUE, unless you change the focus within the handler (or you're doing an OCX property page on big Windows).
I haven't done much WinMob/CE development -- I've been doing big Windows for 15+ years, so window message handling is pretty much second nature. I started doing Windows development back in the days when you didn't have C++ or MFC boilerplate; you had to implement your own DialogProc, crack the messages yourself, etc. It's a lot easier now.
CommandBar / MenuBar
I'm back.. with more questions
Not much of a major issue, but rather an annoying thing I've found. Probably that's what evc/mfc/m$ intended to do that.
Anyway, I'm starting my way of getting around CommandBar. I created a MFC skeleton, studied the code, and that's what I've found, after I've created a CommandBar/MenuBar on evc and putting it in
Code:
if(!m_mainMenuBar.Create(this) ||
!m_mainMenuBar.InsertMenuBar(IDR_MAINMENUBAR) ||
!m_mainMenuBar.AddAdornments() ||
!m_mainMenuBar.LoadToolBar(IDR_MAINMENUBAR))
{
TRACE0("Failed to create IDR_MAINMENUBAR\n");
return -1; // fail to create
}
where I have the variable 'CCeCommandBar m_mainMenuBar' and I have created a MenuBar on evc with the Id 'IDR_MAINMENUBAR'. The menu bar works flawlessly on my dialog based application, when I have the 1st level as a pop up. Example
MenuBar --> 'File' --> 'New', 'Save'
Where 'File' is a folder-like thing that pop-ups and show the contents (i.e. in this example, 'New', and 'Save'). However, given the SAME code to load the CommandBar/MenuBar, it will not work, if I were to put the actual command at 1st level. Example, this will not work
MenuBar -> 'New', 'Save'
where there isn't any folder-like pop-up to store the commands 'New', and 'Save'.
I know that I can have buttons for these commands, and probably works. But, what I'm trying to do is to utilize the bottom-left-right softkey in WM5/6. If I were to have the 'File'->'New','Save' structure, it works fine with WM5, showing it as a softkey. But, if I were to do just 'New','Save' it will not show up in both WM2003 emulator and WM5.
As a matter of fact, even if I have (say) File->New,Load, and I added a new command (i.e. not folder-like-pop-up), example 'Help' on the CommandBar/MenuBar, the File->New,Load will not show up too. It seems like the 1st level command (ie. without a folder-pop-up), causes some problems and stop it from loading further.
Guys, ring any bell?
two bytes more
levenum said:
Hi hanmin.
Odd I didn't notice this thread sooner.
Any way if you still having problems with this code here is the solution:
You are working with char and strcpy so your text is in ASCII (each letter one byte).
But you are calling SetClipboardData with CF_UNICODETEXT so it expects WCHAR (UNICODE) where each letter is two bytes.
The strange letters are the result of two consecutive bytes being interpreted as a single letter (probably lends you in Chinese or Japanese region of the Unicode table)
Windows mobile doesn't usually work with ASCII so the text you get from the edit box will already be in Unicode and won't give you any trouble.
The code should look like this:
Code:
//put a test char
CString test; //since you are working with MFC save your self the trouble of memory allocation
test = L"The text I want on clipboard"; //The L makes the string Unicode
//codes you've given
if(OpenClipboard()) //OpenClipboard(NULL) gives me error
{
EmptyClipboard();
//not sure why you need to copy it again, but here goes:
HLOCAL clipbuffer = LocalAlloc(0, test.GetLength() * 2); //remember: every letter 2 bytes long!
wcscpy((WCHAR*) clipbuffer, (WCHAR*)(LPCTSTR)test); //LPCTSTR is an overloaded operator for CString
SetClipboardData(CF_UNICODETEXT, clipbuffer);
CloseClipboard();
//szMsg probably belongs to some larger application and is irrelevant
LocalFree(clipbuffer);
}
I never used the clipboard APIs my self so I can't guide you farther but this code should work.
Hope this helps.
Click to expand...
Click to collapse
I know it is a bit late! But there is a mistake the code snippet:
HLOCAL clipbuffer = LocalAlloc(0, test.GetLength() * 2); //remember: every letter 2 bytes long!
needs to be
HLOCAL clipbuffer = LocalAlloc(0, test.GetLength() * 2+2);
the terminating 0 is als 2 bytes long!
Those errors are sometimes fatal, with very less chance to find them!
ms64o

VB.Net + Multiple Databases

Hey Guys!
I need a little help in Sql Database programming in vb.net!
how can i Connect to 2 Databases and Join their queries?
Code:
Dim SQLcon As SqlCeConnection = Nothing
Dim strPDAPfad As String = AppDir & "\Catalogs\" & Config.QuestionFileName
Const strPDAPasswort As String = ""
SQLcon = New SqlCeConnection("Data Source=" & strPDAPfad & ";" & strPDAPasswort)
SQLcon.Open()
Dim SQLString As String = "SELECT * FROM QUESTIONS WHERE ID = '" & QuestionID & "'"
Dim SQLQuery As SqlCeCommand = New SqlCeCommand(SQLString, SQLcon)
i want to join 2 databases so i can order one table with the help of another!
Just Like I would have one Database with 2 Tables
"SELECT Questions.ID FROM Questions ORDER BY Stats.Wrong DESC"
I think this is not possible to to it directly. You might need to load the data of one into a temp table in the other db and then do the query.
Would be bad I need to do this very often
I will try to find out how to attach both files to an SQL Compact server and try that again
[edit] found nothing!
scilor said:
Hey Guys!
I need a little help in Sql Database programming in vb.net!
how can i Connect to 2 Databases and Join their queries?
Code:
Dim SQLcon As SqlCeConnection = Nothing
Dim strPDAPfad As String = AppDir & "\Catalogs\" & Config.QuestionFileName
Const strPDAPasswort As String = ""
SQLcon = New SqlCeConnection("Data Source=" & strPDAPfad & ";" & strPDAPasswort)
SQLcon.Open()
Dim SQLString As String = "SELECT * FROM QUESTIONS WHERE ID = '" & QuestionID & "'"
Dim SQLQuery As SqlCeCommand = New SqlCeCommand(SQLString, SQLcon)
i want to join 2 databases so i can order one table with the help of another!
Just Like I would have one Database with 2 Tables
"SELECT Questions.ID FROM Questions ORDER BY Stats.Wrong DESC"
Click to expand...
Click to collapse
Dim SQLString As String = "SELECT * FROM tbl1, tbl2 WHERE tbl1.ID = tbl2.ID and tbl1.QuestionID = '" & QuestionID & "'"
Thank you But I want to do this out of 2 Databases not out of 2 Tables!
I have not actually had the need to do so.
But I would check out LINQ, I have a feeling it should be able to do that.
I'll check it for you when I get home (at work at the moment).
LINQ how it works? I only find rare information for it!
how can I use it in VB.net 2008 ?
There is SQL Command named
UNION
which can Combined Identical Structure Database to Combine the Record from Both Table have you tried it
But how can I use that practically, i know in php is that easily because I know the alias of the Database but with my technic
New SqlCeCommand(SQLString, SQLcon)
there only can be one Database Per Connection
LINQ will read all the records from both databases into memory then do the merge join and give you the matched resultset. You could probably do it much better yourself. If you are going to repeat this join often, then for the sake of the user's patience, you should at least try to do it yourself.
If one table is known to be smaller (in KB) than the other, then I would cache that table in a Dictionary<keyColumn, DataRow> construct. Then I would open a data reader on the second table and process each of those rows by referring to the cached version of the first table.
Of course, I assume you have already ruled out the possibility of permanently merging the two databases? That would be the best solution. But perhaps there are two separate applications, to which you do not have the source code, responsible for maintaining these two databases, in which case I fully understand.
I need to Seperate both!
It is for my Driving Licence Trainer. and I want to Seperate Training Files from the Statistics
If one table is known to be smaller (in KB) than the other, then I would cache that table in a Dictionary<keyColumn, DataRow> construct. Then I would open a data reader on the second table and process each of those rows by referring to the cached version of the first table.
Click to expand...
Click to collapse
@ftruter Could you make an Example for using it for sorting?

Application1 to control App2 (VisualStudio2008)

Hello!
I'm developing one application in VS2008 for my pocket pc, and I need some help to continue with it.
I need to make the buttons of the application1 run even when the application2 is running and try to control it with application1 buttons, but I donĀ“t know if it's possible!?
For example, is it possible to move between items on "windows mob. file explorer" using the up and down keys/buttons of application1?
The application1 only fills 1/3 of the screen, and I still seen windows explorer
When I try to do it, the application1 came to the "top" and windows file explorer control seems to be disable.
Is it possible? Any tips for it?
Regards
Have a look into the SendMessage API call. It should be able to do what you want.
Northernmost said:
Have a look into the SendMessage API call. It should be able to do what you want.
Click to expand...
Click to collapse
I agree. You basically need to catch WM_KEYDOWN messages (and any other you want to pass) and send them to file explorer... I think the tricky part is knowing what application is running directly underneath yours. Post here how you did it if you manage to achieve all that
Arlanthir said:
I agree. You basically need to catch WM_KEYDOWN messages (and any other you want to pass) and send them to file explorer... I think the tricky part is knowing what application is running directly underneath yours. Post here how you did it if you manage to achieve all that
Click to expand...
Click to collapse
Hi!
Ok, I will post here the code of application. Take a look at it and say something about.
Here goes the code:
Code:
Imports System
Imports System.Runtime.InteropServices
Public Class Form1
<DllImport("coredll.dll", CallingConvention:=CallingConvention.Winapi, CharSet:=CharSet.Unicode, EntryPoint:="keybd_event", SetLastError:=True)> _
Public Shared Sub keybd_event(ByVal bVk As Byte, ByVal bScan As Byte, ByVal dwFlags As Integer, ByVal dwExtraInfo As Integer)
End Sub
Private Sub ExitButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ExitButton.Click
'Bye!
Application.Exit()
End Sub
Private Sub UpButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles UpButton.Click
Const VK_UP As Byte = &H26
keybd_event(VK_UP, 0, 0, 0)
'Up
End Sub
Private Sub LeftButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles LeftButton.Click
Const VK_LEFT As Byte = &H25
keybd_event(VK_LEFT, 0, 0, 0)
'Left
End Sub
Private Sub DownButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles DownButton.Click
Const VK_DOWN As Byte = &H28
keybd_event(VK_DOWN, 0, 0, 0)
'Down
End Sub
Private Sub RightButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles RightButton.Click
Const VK_RIGHT As Byte = &H27
keybd_event(VK_RIGHT, 0, 0, 0)
'Right
End Sub
End Class
Do you think it is possible to control any other application with this?
I don't want only control windows explorer, I want to control other applications, including games.
Tanks for help.
Regards
I'm not getting what you want to do with it.
You're designing something like a userbar that's always staying on top but letting you interact with the application directly underneath it;
OR
You're making a "remote control" application to send various commands to different programs, which you specify hardcoding.
Now the control is an easy one (at least in C++) but actually getting what application is underneath yours may be tricky. Can't help much more there, specially with another language. Have you searched msdn?
Hello.
So, I mean to do a virtual d-pad cause I have one of my pocket pc dont have any!
See this post
This is what I want to do.
I think this will be, like you said, a little bit "tricky".
But, if some one could help, I think it will work.
I don't have many skills programming mobile applications.. so every tips and examples are welcome.
Regards
What? That changes everything! xD
On the first post you said you wanted to make the "up and down buttons" sent to app1 change app2... Well, I thought you were talking hardware keys here
(thus the WM_KEYDOWN event)
What language are you using and in what way do you interact with the touchscreen? Did you understand when I said you had to catch the events?
Basically, you want to catch touchscreen (mouse) events, compare the mouse coordinates to those of your buttons (let's say it was a MOUSEDOWN in the LEFT button area), get the window directly below you and post a WM_KEYDOWN message with the LEFT code to it.
The only problems in doing this in C++ for me right now (I'm also a beginner ) would be creating a window that doesn't cover the screen and getting the window below. The rest is really easy
Arlanthir said:
What? That changes everything! xD
On the first post you said you wanted to make the "up and down buttons" sent to app1 change app2... Well, I thought you were talking hardware keys here
(thus the WM_KEYDOWN event)
What language are you using and in what way do you interact with the touchscreen? Did you understand when I said you had to catch the events?
Basically, you want to catch touchscreen (mouse) events, compare the mouse coordinates to those of your buttons (let's say it was a MOUSEDOWN in the LEFT button area), get the window directly below you and post a WM_KEYDOWN message with the LEFT code to it.
The only problems in doing this in C++ for me right now (I'm also a beginner ) would be creating a window that doesn't cover the screen and getting the window below. The rest is really easy
Click to expand...
Click to collapse
Hi!
I'm using Visual Studio 2008 to code it.
Creating a window that cover only 1/3 of the screen, in VisualStudio is not difficult. If you have VS2008, I can send you the project for your email and so you can take a look at it.
If I understand, you can make this work coding it in C++, so we can share both parts... the 1/3 screen window and the way to make app1 control any other app2, cause I have no idea how to make app1 control app2!!!!!
Tanks.
all bull ****
Guys This Is Crap>>>>>>believe Me
jawad786 said:
Guys This Is Crap>>>>>>believe Me
Click to expand...
Click to collapse
?? Why this "is crap" ??
It's a mobile application development try like any other one!
ImpactMan said:
Hi!
I'm using Visual Studio 2008 to code it.
Creating a window that cover only 1/3 of the screen, in VisualStudio is not difficult. If you have VS2008, I can send you the project for your email and so you can take a look at it.
If I understand, you can make this work coding it in C++, so we can share both parts... the 1/3 screen window and the way to make app1 control any other app2, cause I have no idea how to make app1 control app2!!!!!
Tanks.
Click to expand...
Click to collapse
You are aware that Visual Studio actually lets you code in different languages, I hope.
Arlanthir said:
You are aware that Visual Studio actually lets you code in different languages, I hope.
Click to expand...
Click to collapse
Yes. I know that!
So, you think in C++ is possible to make it work?
Have any idea how to? Any tips?
Tanks for help.
Regards
I've already told you what I do know, now for the rest someone has to dig up the information from msdn... I don't have the time right now, as I'm working on something else on the little spare time I have But if you do find a way to do the rest I'll gladly help you with what I can do now.
Arlanthir said:
I've already told you what I do know, now for the rest someone has to dig up the information from msdn... I don't have the time right now, as I'm working on something else on the little spare time I have But if you do find a way to do the rest I'll gladly help you with what I can do now.
Click to expand...
Click to collapse
OK. Tanks for your availability.
I will try to make some progresses... Let you know than.
Regards.
Google is your friend - http://www.google.co.uk/search?q=compact+framework+sendmessage+send+keystroke
Top of the list (http://www.c-sharpcorner.com/Forums/ShowMessages.aspx?ThreadID=40803) looks promising. Note the use of PostMessage rather than SendMessage. It appears SendMessage requires the target app to have focus to work reliably... where as PostMessage doesn't. You learn something new every day
dont know if ur coding something to control only one specific program, but if its for all programs maybe a sip input panel do the same in an easier way
Northernmost said:
Google is your friend - http://www.google.co.uk/search?q=compact+framework+sendmessage+send+keystroke
Top of the list (http://www.c-sharpcorner.com/Forums/ShowMessages.aspx?ThreadID=40803) looks promising. Note the use of PostMessage rather than SendMessage. It appears SendMessage requires the target app to have focus to work reliably... where as PostMessage doesn't. You learn something new every day
Click to expand...
Click to collapse
Tanks for the links.
I've already take a look at it, and now I'm going to try understand it and try to adapt something like to my application.
I will see the to ways... PostMessage and SendMessage.
Regards.
Keep the development goin! Looks like a very interesting project I'll keep track, since I have an Omnia anyway.
Unfortunately I cannot help since I'm a begginer still stuck on Turbo C++ 3.0 (LOL, seriously-awesome right?)

[App][Apr 24 2010] PlaySound - Command line sound player / vibrate for scripting

Description
I had a need to play a sound and vibrate my phone in a script-like setting (specifically, actions in the amazing Rhodium Keyboard Controller app). I couldn't find a simple app to let me do this. So I wrote one! It took about 10 minutes. I now share this with you because I'm sure somebody else has had the same need.
Tip Jar
Like this app? Want more like it? Tip a buck (or Euro or Pound or whatever) or two to help the author out! Click here to make a safe donation via PayPal.
To Use
1. Copy the PlaySound.exe file somewhere, like \Windows.
2. In your script or LNK, use command line arguments to tell it what to do. A single command line argument means that you are specifying a path to a sound to play. It will only play WAV files (sorry if you want WMA or MP3 etc you will need to convert). If you specify two arguments, it means you want to vibrate the phone. The first argument is the LED index of the vibrate (usually 1), and the second is length of time to vibrate in milliseconds.
3. If you do not specify command line arguments, or specify invalid ones (wrong path, negative number, etc.), it will fail without any notice (run, then immediately quit). This app will not tell you when something goes wrong.
Examples
Play the loudest.wav sound in \Windows
playsound.exe \windows\loudest.wav
Vibrate a Touch Pro 2 for half a second
playsound.exe 1 500
Notes
Remember to enclose the path in quotes if you have spaces in the path name to your file, or else PlaySound will interpret it as multiple arguments and think you want to vibrate. (for example, playsound.exe "\Program Files\My App\Sound.wav")
License
This app is released into the public domain with no warranty. That means you can redistribute it at will and do not even have to give me credit. I would appreciate credit, though. ;-) Enjoy!
Requirements
At least WM5 (fully compatible with WM6/6.1/6.5). It should work on touchscreen and non-touchscreen devices both, but I haven't tested it on a non-touchscreen device yet.
Updates
It's highly doubtful that I will ever update this app. If you need more features, feel free to use the source and compile your own!
Downloads
Attached to this post is the app and full source code.
Hi thx1200,
i have seen the following:
if (argc >= 3)
else if (argc >= 2)
Click to expand...
Click to collapse
But not argc = 1 so as in playsound.exe 1 500. Where you have done it, or i am blind .
BTW:
good, easy and clean. Short gec
mike2nl said:
Hi thx1200,
i have seen the following:
But not argc = 1 so as in playsound.exe 1 500. Where you it done, or i am blind .
BTW:
good, easy and clean. Short gec
Click to expand...
Click to collapse
if argc is either 2 or 3 they do their thing and return 0, otherwise the routine follows and returns -1, that's the trigger
EDIT: wait, I think I just said a very stupid thing... this is my second guess: for not knowing ANYTHING about wm programming, I think that argc is the number of arguments passed to the program (as in ARGument Count), while argv[] is the (ARGument Value) index for those parameters
ephestione said:
if argc is either 2 or 3 they do their thing and return 0, otherwise the routine follows and returns -1, that's the trigger
EDIT: wait, I think I just said a very stupid thing... this is my second guess: for not knowing ANYTHING about wm programming, I think that argc is the number of arguments passed to the program (as in ARGument Count), while argv[] is the (ARGument Value) index for those parameters
Click to expand...
Click to collapse
You are correct. argc just counts the number of arguments passed to the application. argv contains the arguments. To make it more confusing, the application path is also passed in. So argv[0] is the app path, argv[1] is argument 1, argv[2] is argument 2, etc. So, argc (argument count) is 2 when there is actually one argument passed in (because the first argument is the app path and the second the first argument).
argv is a string array, so you have to convert the string into a numeric value if you want to do numeric processing, and that's what the _ttoi() function does for the LED index and wait value.
And, there you have it.

help with my time organizer app

I'm developing an organizer app as my bc. thesis and I don't have any real Android developer to consult, so I made this thread and hope somebody will help me and point me in the right direction.
I just started to work on it and I have roughly 1 month to make something useable out of it.
So... the first thing that comes to my mind right now is synchronization.
1. I don't know if I should implement it or not.
I have a hosting with 1.5 GB space, a relatively fast connection. Would syncing data (text (probably xml) only) with this server slow it down significantly ? How many users could an average server take ?
And another one regarding sync:
2. I'd like my application to exchange data with my server under the google account on which the device is logged in, so no registration will be neccessary (I suppose the majority of devices are loggen in with google). I'll probably need to get the user's google account name on every sync session. Is that possible ?
The app will already have a server-side app to edit your events and stuff, so I'll need the user's login information again to retrieve his data from my database, but I won't have his password, so I can't make a usual login form. I guess Google has some API to figure out if a user is logged in, doesn't it ?
Any advice will be appreciated.
Can I open a menu with a simple button click ? Like a context menu but for short clicks.
// I solved the **** outta this one.
Still waiting for answers on the first post.
"Organizer App" really doesn't tell us what you're trying to do. It's hard to answer questions if one doesn't know that basic plan of the project you're trying to create.
Check this -> Basic info about my bc thesis
Nice web page...ambitious project for a 4 week time frame.
As a programmer, you know to start small and add functionality as your program grows.
I would start by making a simple"To Do" list: Add item, Delete item, Edit item, Mark item done, Save this list, Recall a list, Delete a list.
Post back when that's done
Rootstonian said:
Nice web page...ambitious project for a 4 week time frame.
As a programmer, you know to start small and add functionality as your program grows.
I would start by making a simple"To Do" list: Add item, Delete item, Edit item, Mark item done, Save this list, Recall a list, Delete a list.
Post back when that's done
Click to expand...
Click to collapse
Agreed 100%.
@ OP:
I don't know much about syncing, but it won't have a large cost of the server's resources - syncing an CSV or XML file is pretty trivial. Even if you have a low bandwidth cap, text files are quite small. So you should be fine in terms of that.
Nobody can give you a "set number" - ie. the server can take "X people." It greatly depends on the server type, how much bandwidth is allocated to you, your traffic priority, etc. I mean if it's one server with like a xeon processor then it can probably handled a pretty heavy load (say 50 probably? (and yes, I'm kind of pulling that number out of my ass)). Though most web hosts don't just dedicate one server to each customer. Typically, now-a-days, everything is virtualized. Everything is unified using server farms (ie. multiple servers or computers) virtually, then virtual chunks of resources are distributed to clients. So even if somebody could give you exact numbers (which is impossible), they'd most likely be wrong. That is unless you paid extra to have a particular server or particular number of servers dedicated to you...but even then, there's a high chance that it's just a chunk of a virtual server farm.
He's right, this is pretty ambitious in a 4 week period, especially if you have other activities going on as well. It's even more ambitious if this is your first app. You may want to reconsider your objectives given your time frame.
As for the google login, you'd need to look at the google API, and see if there's a way to verify peoples' usernames and passwords. If you can, then it's just a matter of encrypting them and storing them in a properties file or something.
Hope that helps ya out some.
Rootstonian said:
Nice web page
Click to expand...
Click to collapse
Thank you
I know, I know. I could have started 4 months ago. But I didn't, the lazy bastard I am.
This is the practical part of my bc thesis. The ultimate deadline is 3rd of june, but I have to have my theoretical part (30-50 pages of text, if IIRC) done by then, all printed out and ****. So I plan to work as hard as I can on this till the end of this month and then start to work on both at the same time. I really don't have any other duties in school, since I have a nice reserve of credits so this is my priority #1.
The main objective is geo-tasks, since that's what the name of my thesis says. Everything else is just an addition (i.e. the widget, that was just an idea, I doubt I will have time for that). So I'd rather start with that (I know, It's the hardest part). Or do you still think I should start with the to-do's ?
You can check out my last night's post to see what I've been up to the last 2 days and what I'll be up to next.
What is your level of Android programming experience (None, Basic, Intermediate, Advanced)?
And I'm a little fuzzy on the whole "Geo" thing. Is it like I have a list "Get milk, bread eggs", "Pick-up dry cleaning", "Get oil change" and then your app is going to "sense" when I'm by the grocery, dry cleaner's and oil change place? Which grocery? I use 4 different stores. Same dry cleaner and oil change though usually.
If so, you are going to need to code in lat/long coordinates for these places and then compute your location vs one of the merchants, compare that merchant to an "active" TO DO list item and pop-up an alert of some sort if you're within a mile. Wow
Your project, you know your skill level. Start where you want I guess LOL.
I think it's more of an agenda type thing - that syncs.
@Rootstonian
I'd say basic, but quickly crawling up to intermediate.
It's almost like you said, but there's only one location for every task. Maybe in a later version...
Well, good luck. Keep us posted
Will do. Hope you guys will keep on helping me
I need to use my database object in more than one activity. How do I pass it from one activity to another ?
Should I create a new instance in each activity ? Or should I create a content provider ? (I'd rather not - they're quite complicated for me and I only need to access the DB in this app).
I'm going to assume you are using a database helper type class.
No need to pass data from Activity to Activity; just open, use and close the database in each Activity as required.
I have a problem.
I created a LinearLayout for all the tasks in the database. Now I want to register all of them for a context menu. I can do that, but I can't figure out which one's menu was triggered.
LinearLayout has a setId method, but it only takes integer values, which is no good for me, because I have 3 types of tasks and if I assign them their id from the database, then the same ID will probably be assigned to 3 different views.
I could use some sort of multiplication, like for timed tasks I would multiply the ID by 10 000, but that's not elegant at all, and it would crash after a few months of using the app.
So what do I do now ?
I'll paste some code.
Code:
public void drawTasks() {
TextView emptyText = (TextView) findViewById(R.id.empty_todo);
if (tasks.isEmpty()) {
emptyText.setVisibility(View.VISIBLE);
} else {
emptyText.setVisibility(View.GONE);
Iterator<Task> it = tasks.iterator();
//create views
while (it.hasNext()) {
//create a temporary object
Task tmpTask = it.next();
//get it's properties
long id = tmpTask.getId();
String title = tmpTask.getTitle();
String description = tmpTask.getDescription();
int important = tmpTask.getImportant();
int finished = tmpTask.getFinished();
//create new LinearLayout for this task
LinearLayout newTaskLayout = new LinearLayout(this);
newTaskLayout.setId((int)id);
newTaskLayout.setOrientation(LinearLayout.VERTICAL);
newTaskLayout.setPadding(5, 0, 0, 10);
taskLayouts.add(newTaskLayout);
//create new views for these properties :
//title
TextView newTaskTitle = new TextView(this);
newTaskTitle.setText(title);
newTaskTitle.setTypeface(null, Typeface.BOLD);
//important tasks are highlighted
if (important == 1)
newTaskTitle.setTextColor(Color.RED);
//finished tasks are italic
if (finished == 1)
newTaskTitle.setTypeface(null, Typeface.ITALIC);
//description
TextView newTaskDescription = new TextView(this);
newTaskDescription.setText(description);
if (finished == 1)
newTaskDescription.setTypeface(null, Typeface.ITALIC);
//add views to this tasks' LinearLayout
newTaskLayout.addView(newTaskTitle);
newTaskLayout.addView(newTaskDescription);
//add new linearLayout to tasksRootLayout
tasksRootLayout.addView(newTaskLayout);
}
}
}
This is self-explanatory. taskLayouts is an ArrayList of LinearLayouts where I keep the pointers to all layouts that need to have a context menu.
There are 2 other similar methods: drawTimedTasks() and drawGeoTasks() which do basically the same (I couldn't figure out a way to do it with one universal function).
Here's how I register them for context menu:
Code:
private void registerViewsForContextMenu() {
//register control bar buttons
registerForContextMenu(newGeoTaskButton);
registerForContextMenu(newTaskButton);
Iterator<LinearLayout> it = taskLayouts.iterator();
while (it.hasNext()) {
registerForContextMenu(it.next());
}
}
And here's how I'm checking for context menu trigger:
Code:
public boolean onContextItemSelected(MenuItem item) {
switch (item.getItemId()) {
case ...
return true;
}
...
}
return false;
}
What am I doing wrong ?
Anyone ?
----
I haven't really been following this thread so I don't know all the details of your app, but I'll try to help.
So each task has 3 views for it? Each task is in the db once? I'm a little foggy on how you're storing them and what the correlations are between views, events, and types of event, more specifically the latter.
If you explain that a little more clear, I can try to help a little better.
There are 3 types of tasks : simple, timed, and geo tasks. Each type has its own table in the db, hence it's own IDs. That means, the first geo task, first simple task, and the first timed task ever added have all the same ID = 1. That means if I want to give their views unique IDs, I can't use their IDs from the database.
So I'm trying to figure out a way how to give the view ID's so I can find out which database record they represent.
In an ideal world, I would be able to define a string ID (i.e. geo_1, simple_1, timed_1), but this is not the case. I dunno why... in XML you give your views string IDs, but programatically you can't.
grandioso said:
There are 3 types of tasks : simple, timed, and geo tasks. Each type has its own table in the db, hence it's own IDs. That means, the first geo task, first simple task, and the first timed task ever added have all the same ID = 1. That means if I want to give their views unique IDs, I can't use their IDs from the database.
So I'm trying to figure out a way how to give the view ID's so I can find out which database record they represent.
In an ideal world, I would be able to define a string ID (i.e. geo_1, simple_1, timed_1), but this is not the case. I dunno why... in XML you give your views string IDs, but programatically you can't.
Click to expand...
Click to collapse
If all of the tasks have common elements (even if they don't really), you can merge them into one table. Then define an enum or something for the task type, as a simple field in the table. This removes the issue with duplicate ID's, while still being able to differentiate what type they are. You can typically leave fields blank in a database, so you wouldn't have to worry about what's filled in for tasks that don't have particular fields associated with them, just verify all fields prior to mutating the database.
If you're hellbent on keeping three separate tables you can hold a global ID, which can be an intersection between all three tables. So this wouldn't be the primary key, just a global ID, and you can key them up by that. Not entirely sure where you'd keep it to persist over power cycles unless you just make a 4th table with one row and store it in there. Or just throw it in the program's data somewhere.
The reason you can define things in the XML is he XML is compiled into the R class at compile time...though everything in there *should* have a corresponding methodology to get it done programatically. Though if you're talking about the primary key, as far as I know that is always numerical. So the ideal world may not apply - BUT, that doesn't mean you can't create a field that stores a string id (which I wouldn't, because string comparisons take a lot of time, but whatevs).
Hope that helps you out some, I don't really touch databases and am very new to Android programming, just know what I know from absorbing info from others - but I know a pretty decent amount about programming in general and know Java pretty well so I can probably help you out the best I can in some respects.

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