Protect Database Against Corruption?
May 25, 2005
I have a split database. BE located at a server and FE on each users workstation. There are 8 concurrent users at the most. This runs smoothly over the LAN.
Now I'm adding a new feature to the database. I'm using a wheel loader to weigh products on a weight scale. The operator in the wheel loader is going to use a laptop with wireless LAN to connect to the network.
In risk of loosing the connection which in worst case might corrupt the database, I want to make a new database with a BE/FE setup. The BE will be placed on the same server as the current db. The FE in the wheel loader. I can then link from the current db (BE) to the new db (BE).The new db will only require two linked tables from the current db.
If worst case happens, would my current db be more protected against corruption than if I linked directly to the BE on the current db. I know there's no 'right answer' to this one, but I'd really like some opinions on it though.
Thanks in advance.
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Jul 12, 2005
I am trying to open a database that has been run on a network and now keep getting this error message
"The Microsoft Jet database engine stopped the process because you and another user are attempting to change the same data at the same time"
And wont open the Database.
Any way round this or am i fighting a lost cause?
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Feb 3, 2006
I inherited this user written multi user (<=10 simultaneous users) Access 2000 database. The front end in Access 2000, the back end is SQL 2000. All the tables are linked to SQL.
When the users were running the Access front end on a Novell server there were no problems. We have sinced moved it to a Windows 2000 server and are now getting a Database needs to be repaired message 2 or 3 times a day.
I searched the web and the only thing I came up with is that the Opportunistic Locks Setting on the Windows 2000 server needs to be disabled.
Naturally our server team is reluctant to change the settings.
Has anyone else experienced this problem or have any suggestions?
Right now our solution ws to put a copy og the Access frontend on each user's C:, very ugly and difficult to maintain!
Thanks so much for your help!
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Aug 21, 2006
Viewing an email from Code Project, I ran across this article about database corruption and thought it was worth posting here...
Be sure and click on the immediate link below to view the latest updates in the discussion area at the bottom of the web page.
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http://www.codeproject.com/useritems/rdb.asp
Strange behaviors of an access database
By Hamed Mosavi.
Introduction
A while ago I encountered a strange behavior in my application which was using an access database (.mdb file). I placed a question in the CodeProject C++ forum, and I did not get any answer. I started searching the web, MSDN, etc... and I found out that it's not all my fault. I found the reason in a knowledge base article. Look at it's description about the possibility of corruption of an access database file:
"There are several things that can happen, both inside and outside of Access, that may leave your database file damaged (corrupted). The symptoms of a corrupted database can range from #Deleted appearing in certain records, to you being unable to open one of the objects in the database, to you being unable to open the database file in Access altogether." (MSDN-Knowledgebase:283849)
Since I got no answer for my question in the forum, I thought there are at least some guys out there who might don't know this , and also since it's easy to corrupt a mdb file, while it's difficult to understand the reason why the application is not Functioning properly, I started writing this article.
The question is what might cause a damaged access mdb file and also how to repair a damaged access file programmatically.
Background
What can cause the mdb file to corrupt
The knowledge base says:
"There are three main reasons why an .mdb file may become corrupted, as follows:
* Interrupted write operation
* Faulty networking hardware
* Opening and saving the .mdb file in another program"(MSDN-Knowledgebase:283849)
There's a detailed description for each one of these in the knowledge base, but some of important reasons are as follows:
* Losing power during database write
* Dropping network connection
* Abnormal termination of microsoft Jet connection, such as having task manager to shutdown application, power loss, manual shutdown. (notice that:Fatal system errors almost always cause abnormal termination, refer to kb to find out more information)
* Forgetting to close ADO or DAO objects that opened. (Objects from classes like:Recordset, QueryDef, TableDef, and Database)
* A large number of open and close operations in a loop (more than 40,000 successive open and close operations could cause corruption)
* And worst of all, Opening and saving the .mdb file in another program like MS word. It is not recoverable. all your data will be lost.
"There is no way to recover an .mdb file that was opened and then saved in a different program"
(MSDN-Knowledgebase:283849)
How to reduce corruption possibility
* Avoid all above
* Compact the database often (The class provided with this article)
Things can get worst
Q291162: AutoNumber field duplicates previous values after you compact and repair a database:
Microsoft also announces that after we compact and repair our database, it is possible to encounter Duplicate Autonumber field, and if it's your database key, then...
fortunately this applies just to those who are using Microsoft Jet version 4.0.2927.4 and earlier. "Microsoft has confirmed this to be a problem in Microsoft Jet version 4.0.2927.4 and earlier." (MS KB Q291162). to find out your Jet engine version try to search your system/32 directory for Msjet40.dll (if you are using v.4 and later) then get the properties of the file. This KB can help you find your version and download latest version:Q239114
Another bug exists there and it's "AutoNumber field is not reset after you compact an Access database" I don't describe a solution for this, since there is one already, and it is not really critical, for more information refer to KnowledgeBase Q287756.
if you lost data and have problem recovering data(yet), this can help you a lot: Q247771 and Q306204.
Using the code
In order to use the code, follow the following steps:
1- Copy DBFitter.cpp and DBFitter.h to your project.
2- Check and possibly change first two #import directives in DBFitter.cpp.
#import "D:PROGRAM FILESCOMMON FILESSystemadomsado15.dll" rename( "EOF", "MSADO_EOF" )
#import "D:PROGRAM FILESCOMMON FILESSystemadoMSJRO.DLL" no_namespace
3- include DBFitter.h, Create an object from type DBFitter and use it as follows:
CDBFitter fitter;
if ( !fitter.CompactAndRepair(szDbPath,m_szDBPass) ) {
AfxMessageBox(fitter.GetLastErrString());
}
CompactAndRepair has 3 forms that can be used alternatively. The first one you see above , The other form just gets database file path as input and does not use password
CompactAndRepair(CString szDbPath)
The last one asks for a source, a destination and password, which can be given "" as password to say there is not a password
CompactAndRepair(CString szSrcDbPath, CString szDstDbPath, CString szDbPassword)
4- Don't forget to call AfxOleInit(); in the initialization of your application.
"What to Make Sure of Before You Run the Compact and Repair Utility
Before you run the Compact and Repair utility on a database, make sure of the following:
* Make sure that you have enough free storage space on your hard disk for both the original and the compacted versions of the Access database. This means that you must have enough free storage space for at least twice the size of your Access database on that drive. If you need to free some space, delete any unneeded files from that drive, or, if possible, move the Access database to a drive that has more free space.
* Make sure that you have both Open/Run and Open Exclusive permissions for the Access database. If you own the database, make sure to set these permissions. If you do not own the database, contact its owner to find out if you can get these permissions.
* Make sure that no user has the Access database open.
* Make sure that the Access database is not located on a read-only network share or has its file attribute set to Read-only. " (Q283849)
Compact and repair in C#
Thanks god, there is already an article: http://www.codeproject.com/cs/database/mdbcompact_latebind.asp
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If there are any questions or feedback; please direct them to the original authors link at the top of the page so everyone can benefit.
Thanks.
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Nov 21, 2007
Dear all,
I believe I have discovered a new way of fixing corrupted forms in Access.
After a crash, one of my forms refused to open in either design or form view saying:
Form name | is misspelled or refers to a form that doesn't exist
Having searched the internet for this error I found lots of people recommending Repair/Compact or copying and pasting the currupt object into a new database.
Repair and Compact (Access 97) both ran successfully but failed to fix the problem.
When I attempted to copy and paste the broken form either within the database or externally I got
Error 13: Out of Memory
When I attempted to import the form into a new database I got
Automation error
If I attempted to rename the form, I got:
The save operation failed
Resolution: (I don't know which step here was the key to my success)
1) Delete all other database objects (all tables, queries, forms, macros and modules)
2) Create a new form and put any control on it.
3) Attempt to save the form using the same name as the corrupt form
4) Access asks "The name you entered already exists..." (Aha! The first time Access is admitting that the corrupt form exists.) Say no to this prompt.
5) I was now able to rename and open my corrupt form. Everything was fine.
If this post stops just one other DBA having to go through the morning from hell I just went through then it'll all have been worthwhile!
Happy coding,
Rob Levy
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Feb 15, 2013
1. How to protect my access database. That is can i only let my boss to use ONLY and not see the struture / table relationship?
2. That i can use access table to call file form my computer desktop outside folder. Can i set the limit time for outside folder?(for example 3 days, after 3 days then the folder will damage or not exist? can i do that?
3. can i set the password and after some days(for example 2days). they cannot go into my access database?
4. can i make my access database only for use only, cannot copy and can i set the life time for my access database (for example maybe 2 days,
the access database cannot open. )
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Sep 6, 2005
Hi,
How can I hide the Database window with password protection?
For example, if someone attempts to access the Database Window, they would be promted to enter the password before they can see the tables and queries...
Thanks for your help
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Aug 11, 2006
I got this "AOIndex is not an index in this table" error with Access 2000 after replicating a database and storing it in the same network folder. I am not able to open my database now, i am afraid 2days work on my forms is lost. I usually have backup, but the last backup i have is 2 days ago i have made alot of changes to 2 FORMS after that :(
Please anybody have suggestions on how to retrive my forms??? I am really concerned about the forms. I have backup for data and for the reports. Please help me?
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May 17, 2006
Hi,
With my database I have actually distributed the mdb file to 2 of my users so that they can make their own reports. I have secured it so that these users cannot delete/modify anything they shouldn't.
However every so often it seems to get corrupt. I did decompile it and I tried importing everything into a new DB and secured it again. It seems to be working again but I wasn't able to find what was corrupt so I'm not completely confident that its fixed.
Would it be better if I gave them the MDE file - would it lessen the chances of it becoming corrupt??
When I leave the job I guess I will need to show someone how to decompile it in case there is a problem?
Thanks
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Aug 31, 2006
Hi guys i will appretiate it any hlp you can give.
A few weeks ago i started to experiencing problems with my access2k db. Some times i could open it and sometimes an error like this one.
"Microsoft Access has encountered a problem and needs to close. We are sorry for the inconvenience.
It asks to send a report and to repair the db
more data:
1- my jet engine version is 4.0.9025.0
2- because i eliminated the cross from everyform in the db sometimes i had to close access from the task manager.
3- i have never compacted the database.
4- it is still in development phase, so there are only a few records.
5- In order to use the db i have to use a citrix session in the usa (i am in australia), and from the citrix server connect to another drive in the usa. I also moved the db in the citrix server but i had the same problem.
Question:
if i copy the forms into a new db, will i have the same problem?
thx, max.
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Oct 24, 2006
Hi all,
I have a small database being used concurrently by 5-6 users, in the last few weeks we have had some corruption issues, the users are running a mix of access 2000 & 2003 – would unifying versions help these corruption issues?
Also what is the recommended maximum number of simultaneous users accessing one a DB in a LAN/WAN environment?
Thanks
Jamie
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Jan 21, 2008
I have been searching for an answer to this, but no luck. Has anyone ever seen the below error when loading an Access 2003 database?
"[database name] has detected corruption in this file. To try to repair the corruption, first make a backup copy of the file. Then, on the Tools menu, point to Database Utilities, and click Compact and Repair Database. If you are currently trying to repair the corruption then you will need to recreate this file or restore it fom a previous back up."
The database is already compiled and compacted. It's a new Access 2003 program. Only one user is experiencing this problem. She is on XP while the others are on Windows 2000. Everyone is using 2003. I saw other odd error messages on this machine with other databases, but I was able to avoid them by setting the Macro settings to Low. This is a Network environment. Any thoughts?
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Mar 25, 2008
hi
i'm getting annoyed by Access 2003 (and 97 for that matter!) just corrupting records in a table and then i have to scrabble around, kicking people out the database, compact & repairing, maybe installing the back up copy and in one case, doing a make table query from the data table that excluded the corrupted record
:(
are there any general things i can do to avoid these things, or am i just going to have to roll with them?
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May 9, 2006
i have a users table where i save usernames and paswords. So anyone who has access to the users table and has little know how of access can read the passwords of other users. So I have encrypted these passwords. Now no one can read eachothes passwords but if someone has acess to the database he can copy his encrypted password to someone else's password and login using other people's account.
Any solution ????
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Dec 7, 2006
one form in my database?
I would like to put a password on one form; all other forms are open to see.
Can this be done?
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Jul 12, 2005
Hi all, apologies for the long post but this is a long nightmare!
Using A2k on Win2k...Due to roll out a DB today, just made my final tweaks and decided to compact/backup as have done many times before. It's not a split DB but it is secure so I copied the mdw onto my desktop and accessed it using a special compact shortcut which points to the desktop copy DB not the one on the network. When I compacted though Access went about it's business for a while and then threw up the dreaded "Network connection may be Lost" error message (roughly translates as "your database is nicely corrupt now") which I have had in the past when I tried to compact on the network. I've never had this error before compacting locally but anyway I tried again and same error message. I tried opening some forms and stuff and sure enought the DB was corrupt. No probs I thought, I can just go back to the original and start the process again. I used the normal shorcut to open the original DB just to check everything was ok and the same error message appeared with same problems. Minor panic ensued and I thought i'd got the shortcuts mixed up or something... I hadn't, Both DB's were affected.
Next option. Create a new DB and import all the objects. I did that and re-set all the permissions and the "Network Connection Lost" message dissapeared but some really strange things were happening. Forms opened but the buttons on them would do nothing. Then the forms Close button didn't work and the database wouldn't close.
I forced my way out of the DB and re-started my machine. Couldn't even log in to windows. Now at another machine and can log in to windows but DB is still having same problems. My instict tells me that the problem is something to do with the workgroup file becuase how else could compacting a copy corrupt the original? The only common link is the mdw.
Should I re-create the mdw and then try opening/importing the DB objects again? Or is there any way I can un-secure the DB and then re-secure it later?
Any thoughts would be much appreciated.
Thanks, Tom
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Nov 21, 2006
Hi all..
In my access 2003 application, I can open the database and goto the design view of the Forms..but I cannot view the code. I tried both Alt+F11 and Right click on the form and "Build Even" and "Code Builder".
In both cases, access application stops responding. Then I have to close it using the task manager.
Any ideas how to fix this issue? Thanks in advance for your help.
:confused:
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Jan 15, 2008
I have been experiencing some very strange symptoms over the past week or so, and am looking for ideas. I have a number of different frontends that link to one or more shared backends. A week or so ago, all the frontends were reporting that one of the backends, PCAMaster_be, was corrupt (ie, "not a recognizable database format). I repaired it, it worked ok, and then a few hours later it was corrupted again. After going through this a few times, I rebuilt the be (imported everything into a new, blank db). Same thing -- it was OK for awhile, then became re-corrupted.
So, my conclusion was that:
a) one of my frontends was corrupting it,or
b) my shared library.mde file was the culprit, or
c) my shared .mdw file was the culprit.
I have been meaning to unsecure my db's for awhile becuase I don't really use the security in any meaningful way. So, spent most of the day yesterday going through the steps to unsecure. So, I'm not using anything but the default .mdw file now. I also rebuilt every single FE, BE, and the library.mde.
Now, PCAMaster hasn't gone corrupt again (yet), but I'm noticing several other bothersome symptoms:
1. In one of my FE's, when I close it, the application closes but it leaves Access running. I have to use task manager to get access to close.
2. Some of my .ldb files seem to stick around when they're not supposed to. I am 100% certain that NO ONE is using the db. But the .ldb file is still there and I can't make it go away.
3. I open a FE with the /excl command line option. It opens OK, but when I try to repair/compact, it won't let me. ANd if I try to make design changes, it says I don't have exclusive access.
ANy ideas appreciated on any of this stuff
Using Access 2002 and Windows XP
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Jun 17, 2005
I have an Access 2000 split into FE and BE and the client has requested the BE be password protected. I attempt set database password on BE but then when I open FE I get error msg " not a valid password". I get the same error message if FE has same password or if FE has no password.
Any ideas?
Thanks,
Jim
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Dec 6, 2005
Hello,I need to know is there any way to protect a shortcut on desktop ?Bcz someone is deleting (I dont know by mistake or intentionally) shortcut of database shortcut. I thinking about its protection from deletion only unless you have to supply a password or code something like that.Any idea..?With kind regards,Ashfaque
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Sep 19, 2006
Hi,
Is the password property in Access secure enough to protect VBA code?
Regards,
B
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Aug 28, 2007
Hi
i am wondering if it is possible to password protect a form?
I am building a DB which will hold personal information, all this info will be held in a table and displayed on a form, but I would like it so that the user has to enter their user name and password and only the form which relates to their details opens ( so like an open form and display specific field but passworded)
Any ideas?
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Dec 2, 2004
hi,
Is it possible to password Protect a table in Access 97?
I need to limit who can actually go into the raw data table as even though it is hidden, a user can easily unhide if they knew how.
any ideas?
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Aug 27, 2005
How I can protect the tables in a database and force the users to access them only through 'forms'. In other words the user will not be able to view or change the data in any table except through a form, when loading a form, the protection is diabled.
I need a total solution, I am not a powerful programmer. :confused:
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Jan 25, 2005
Is there a way to password protect a form.
This is due to me having to send a mdb file, because i use A97 and the other end use A2000.
I tried sending the mde file but they could not convert it etc.
But i want to stop them getting into the code, you know how protective we are.
I want to hard code the password if thats any help.
Could some one please help me, thanks
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Feb 3, 2005
Can someone point me in the right direction of how to protect a button using a password please
cheers
Andy
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