couldn't lock file

This error appears only on one user's computer. The application captures the message and displays it on the screen. I do not have such a message in the app. The application uses a local mdb and is an application client-server. It uses the mdb to get the names for some codes. The application works with some long routes (long list of station codes) and the error appears in these cases (route means a path between two railway locations). For the short routes it is working ok.

Please help me to solve this problem!

Could you provide the exact message? Just use Ctrl+C/Ctrl+V or, at least take a screenshot.

Calipso error "Couldn't lock file"

http://www.google.com/search?num=20&...=&oq=&gs_rfai=

calipso is the name of my application - no connection with calypso. so the page does not respond to my problem.

Quote:

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Originally Posted by florivucu

calipso is the name of my application - no connection with calypso. so the page does not respond to my problem.

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Can't you use google? :confused:
Just remove your "calipso" from the search box! :rolleyes:

http://www.google.com/search?num=20&...=&oq=&gs_rfai=

I'm using google but there is no connection between calipso and calypso. "Calipso" is the name of my app. What appears under the link you gave me is not helping me.

Quote:

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Originally Posted by florivucu

I'm using google but there is no connection between calipso and calypso. "Calipso" is the name of my app. What appears under the link you gave me is not helping me.

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The fact ypo are "using google" doesn't mean (unfortunately! :sick:) that you can use it! :thumbd:
Again: http://www.google.com/search?num=20&...=&oq=&gs_rfai=

Before posting this message on codeguru I searched the net for this error. The problem could be easily solved if the error appears all the time. But there are some path (routes) which do not give this error - they are working ok. Thank you very much for your replies but I could not solve the problem.

What is the difference in calculations for "long" and "short" routes?

The thing is I receive from the server a list of codes and to deliver it to the user I search the names in the mdb. From the time te user places the request and before I get to deliver the entire route I get the 'couldn't lock' file message. Even If I press Ok the route delivered is not complete so I can probably get into the mdb file to get some of the names but for some reason it stops.
It's a local mdb file placed on the user's C: directory.
If I request the same route from another computer it works out fine: same mdb (copy-pasted it)
Most of my users don't get this error. It has appered so far on 3 of them.
I checked the rights, I can move-it, delete it etc...

What is the "the user's C: directory"? Does you app have access to this directory (it is what http://support.microsoft.com/kb/306441 explains)?

I've read about this. The user logged in has full control to the directory where the mdb is placed. If I try to open the mdb manually I can even see the ldb file. When I open my application I can't see the ldb. I don't know how to grant rights to my application specifficaly but I think I would have this problem even for the smaller routes, not just the long ones (which is not the case).

Quote:

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Originally Posted by florivucu

... I don't know how to grant rights to my application specifficaly but I think I would have this problem even for the smaller routes, not just the long ones (which is not the case).

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Then again:

1. what is the difference in accessing database for "long" and "short" routes?
2. what is the difference in accessing database in the "problem" PC and all the other ones?

From my application there shouldn't be any difference.
I load the codes from the txt the server gave, get the corresponding names using the mdb and print them onto the screen.
I use:
name=TUILibrary::Get_Name_Station(location);

where Get_name_station is:
long codes = atol(sta_code);
CString sta;
if (codes == 0)
return "";
CStatiiSet RstStatii;
RstStatii.m_strFilter.Format("CODSTA = %ld",codes);
if (!RstStatii.IsOpen())
RstStatii.Open(dbOpenSnapshot);
RstStatii.Requery();
sta=RstStatii.m_DENSTA;
RstStatii.Close();
return sta;
a longer route just means I call this function for over 100 different location codes

1. What happened if you'd move database to some other drive/location (say, in d: )?
2. How do you access your db: via ODBC, DAO, ADO? (it looks like you are using DAO- ?). Are you using try/catch blocks (I don't see any in the code snippet you've posted)

Quote:

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Originally Posted by florivucu

I'm using google but there is no connection between calipso and calypso. "Calipso" is the name of my app. What appears under the link you gave me is not helping me.

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Sheesh
http://www.google.com/#hl=en&source=...6ec6be010d257f

Check the restrictions of the database you're using. It could be you're exceeding some of it's limits. Several database systems limit how many concurrent locks you can set. Or limit the size/complexity of transactions. The limits could be hardcoded (nothing youc an do other than changing database engine). Or they could be restrictions you can change via some settings, increasing the lmits may increase memory consumption and degrade performance however, so again, check the documentation of your database.

The app is accesing the database with both ODBC and DAO. I'm at home now but I'm pretty sure I'm not using any of the try/catch block you mention. I have a feeling that - maybe - on that computer, on the long routes something goes wrong. Maybe while checking for the name it is going too far and the app overwrite some code. Do you think it is possible? I will check also the restrictions but the app works ok in 100 location. Only this is with problems. Again thank you for your support.

Quote:

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Originally Posted by florivucu

The app is accesing the database with both ODBC and DAO. ... I'm pretty sure I'm not using any of the try/catch block you mention.

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Very bad. You have to..., otherwise, you cannot get any useful info in the case something in DAO/ODBC failed.

The function which give us the name looks like this:
........
long codes = atol(sta_code);
CString sta;
if (codes == 0)
return "";
CStatiiSet RstStatii;
RstStatii.m_strFilter.Format("CODSTA = %ld",codes);
if (!RstStatii.IsOpen()) //varianta pt. OpenTable (OLE)
RstStatii.Open(dbOpenSnapshot);
RstStatii.Requery();
sta=RstStatii.m_DENSTA;
RstStatii.Close();
return sta;
....
The user is admin on the machine. The mdb was removed and reinstalled. I could open the mdb and it was ok. Yesterday afternoon the app worked ok on the same long path. This morning it did not work. So, what can it be?

Corrupted .ldb file - ?

no virus found

Quote:

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Originally Posted by florivucu

no virus found

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Virus is a vere rare reason of .ldf file corruption.
Did you try just to delete .ldb file?

no, I did not. What can I expect deleting this file? This file is deleted after closing the app. I asked the user to look aver it but there is no ldb.

Then perhaps, your .mdb file has been corrupted? Try to open it with MS Access or some other App that can work with .mdb files.

I did open the mdb. It is ok. No problems.

What is the statement that causes the lock error?

Is it the RstStatii.Open or the RstStatii.Requery?

If you don't know set a breakpoint to both statements.

In any case I am pretty sure that VictorN is right and the error is related to the kb306441 error when the application has no or no sufficient priviliges for locking the .ldb file. For example it could be a difference whether you copied an existing .ldb file from elsewhere or whether you were not be able to create a new one.

To verify that you simply may create a folder like c:\temp\db and use that rather than using c:\ root folder.

If you encounter the lock errors nevertheless, check whether there is another connection parallel. It could be MS Access or you were using multiple connections in your app.

I cannot use debug - breakpoints - because on that computer we use only the exe file. The last solution is to reinstall Windows and Office, too.

1. Note that to work with .mdb database you don't need to install office at all.
2. Fix your code adding try/catch blocks and displaying message boxes in the cases of exceptions.
3. Implement logging (writing current info in some .txt file)

The user needs to obtain some report these days. I do not have time to implement logging. I put some messages in the app and the app worked ok. But using the app without messages doesn't work any more. To do all you said I need time which I do not have.

may be some simultaneous locking problem from diff users is causing the problem. try to use semaphores or mutex for synchronisation..

I assume the "lock" is about the mdb. On that computer only one user is working. I don't know to use semaphores or mutex.

Quote:

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Originally Posted by florivucu

The user needs to obtain some report these days. I do not have time to implement logging.

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You spent much more time for the long discussion here than you'd needed to implement logging. :cool:

// EDIT: besides, time only matters if your App works, which is, unfortunately, not the case.

Quote:

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Originally Posted by florivucu

The user needs to obtain some report these days. I do not have time to implement logging. I put some messages in the app and the app worked ok. But using the app without messages doesn't work any more. To do all you said I need time which I do not have.

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At least implement the try/catch blocks, catch and report the error. You may learn something.

FWIW, Requery after Open is redundant. You should remove it.

Quote:

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Originally Posted by GCDEF

FWIW, Requery after Open is redundant. You should remove it.

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Correct! good catch!

Or, at least insert else between them!

Code:

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        RstStatii.m_strFilter.Format("CODSTA = %ld",codes);
        if (!RstStatii.IsOpen())       
                RstStatii.Open(dbOpenSnapshot);
        else
                RstStatii.Requery();

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Problem solved. Thanks to all. The problem has been solved by reinstalling the MS Office. I will keep in mind to apply all you said in the new release. Many thanks to all.