I was just wanting some explanation as to what is going on once you have split your tables out into a back end file, and set an mde out for use.
When a user accesses the mde, is the mdb still required to get to the tabes (or in order to make it work)? Let say I put these access apps on a shared drive for folks to use. If I split the be end on to the shared drive, and placed the mde on the shared drive, would I the mdb have to exist for that version mde to work (communicate with the tables)? Or does the mde sort of speak to the mdb which speaks to the tables?
Hope this question makes sense.
Thanks
EDIT:
One additional question: I have an MDE set up on a network share drive, but I was not certain as to whether or not I had to have the mdb present on the same share drive as my mde and back end (tables)....if not then I would prefer to not have it there because user insist on getting into it, and making copies of it and such.....
But my question is, as I said I put A MDE out on a shared drive, which means there is one that about 10-12 people max, share, and the likelihood that even half these folks would be in there at the same time is very very unrealistic. But I recently read that I should have an MDE for each person? Is that true? What is a good example of distributing one to each person? I have only ever gone with the one on a shared appraoch before, and was unaware that this was, if in fact it is, a bad approach?
Thanks for your help!
No the MDE version does not maintain any communication with its original MDB source version. However you want to keep the MDB in a safe place so you can make design changes there, and then create a new version of the MDE from the updated MDB.
The stronger case for an MDE is for the front end application you distribute to your users --- assuming you don't want them changing the design of any database objects. The back end database traditionally contains only tables, relationships, and indexes. You may decide the back end can remain in MDB format.
Edit: Do not allow your users to open the same front end application database, regardless of whether the front end is in MDE or MDB format. Sharing the same front end increases the risk of corruption. They can all still share the same back end with links from the front end to the back end tables.
Tony Toews has made the challenge of giving each user their own local copy of the front end fairly easy. See his useful and free! utility at Auto FE Updater.
#HansUp has done a fine job of answering your actual questions, but I'm posting an answer here just to try to explain what seems to have confused you.
Step back for a moment and consider how Microsoft Word is deployed and programmed.
When you install Word 2007 on your
computer, you don't share it with
other users -- each of you installs
it on your own PCs.
When you install it, you're
installing the compiled application,
not the source code.
Microsoft keeps and maintains the
source code, which you don't need to
run Word on your PC.
The source code for Word is like the
front-end MDB.
The compiled Word EXE and all of its
supporting files is like the
front-end MDE.
Just as with the Word application
files, you don't share it, but give
each user an individual copy of it.
As with Word, your users don't need
the source code to run the compiled
application, so all your users need
is the MDE.
Just like Microsoft, you need to take
care of your source code MDB so that
it doesn't get corrupted or lost, in
order that you can continue to update
it and produce new compiled versions
for your users.
It's not complicated when you understand the function and role of the different parts. It is confusing because of the fact that MS's documentation for Access tends not to promote or explain best practices. I can't quite understand why this is the case after all this time, but it still is.
You're well on the way to doing things properly, though.
Related
I have a quick question: if both my MS-SQL back-end and MS-Access front-end are installed on a shared network drive, can the front-end be opened from different computers and the data still be synced correctly on the server? I am asking because we are having more employees located in different buildings. If possible, it would be easier to manage than walking everywhere to install the front-end.
Two people opened the front-end today and put in clinical cases simultaneously. When they opened it again, everything seemed to have synced, but could something wrong be happening? I am not sure.
if ... my ... MS-Access front-end [is] installed on a shared network drive, can the front-end be opened from different computers and the data still be synced correctly on the server?
What you seem to be describing is more than one concurrent user directly opening the same copy of a front-end file, e.g., one stored in a shared folder like
\\servername\sharename\path\to\frontend.accdb
If so, then that is extremely bad practice. Every user must have their own private copy of the front-end file on their local hard drive. That is what the other answer meant when they said
you only need to have them copy the front-end file to their computer - there's no installation required
In your question you said two users apparently opened the same copy of the front-end and made changes to the data, and nothing bad seems to have happened. They were lucky. Sometimes it works and other times it doesn't, but in my experience it's not a matter of if it will cause problems, it's a matter of when.
Yes it should work OK. If the network connection between the front end and back end database will work from the user's individual computer, then you only need to have them copy the front-end file to their computer - there's no installation required.
I am trying to split an Access database where I work but I have encountered a few issues that I am struggling to resolve. If I can first explain the problem.
I work for a large multi-national company that has on-site IT support but does not support Access (so no help there)
There are 12 of us working in our section, we have an old and badly designed StockMaster database on the networked F drive. The problem is that it is only set up for single users, we have to take turns using it. We aren't a computer savvy bunch, we tend to run the same named queries on a daily basis
The database is only updated once per day, every morning we get a download from our colleagues in Amsterdam. I do not want to play around with this database as first of all I'm no expert and secondly if I break it, no one will fix it.
My plan is this;
I have created a new Access database StockMaster2 that imports the required tables. Using VB coded modules, is deletes the old then imports the new. Therefore every morning it replicates what is in the original database and it works fine.
My next step is to split the database, create the front end and distribute. This is where I'm having problems.
I created the original front end StockMaster2_fe.accde and placed it in the database folder on the F:\ drive. Does every user get their own copy of the front end? I copied and saved two more front ends (copy and paste in the same folder -> rename) namely StockMaster2_alan_fe and StockMaster2_ryan_fe and tested it. I told Ryan (who sits next to me) to find the front end named after him on the F:\ drive and open it whilst I was in ...alan_fe. We both went to run macros at the same time but he was kicked out as it gave me exclusive access.
What am i doing wrong? Why is it not allowing multiple access?
My problem is that due to strict administrator privileges I cannot download any software or access the command line, so anything that I do must be done in Access itself
I apologize for not seeing this post sooner to end your agony. There are two absolute main issues that must be resolved to get you on the right track. First, and perhaps the most important, is that your file has the name of StockMaster2_fe.accde. The extension, the accde, is the executable version. Design changes cannot be made to that version. The extension should say .accdb to provide you with all the flexibility to alter the database, create one database for back-end tables, and a second database for front-end objects to include queries, forms, reports, macros and modules. If you have the accdb version, then your work will start to get much easier.
Issue number two, if your team is not able to share the database, then that is a sign that the database, when first opening, is opening in Exclusive mode. This option can be changed in the Access Options, in the Advance menu, under Advanced section. Look for Default open mode. It should say Shared to have multiple users operating all at once.
A possible hidden issue that can be happening, is that the database has VBA code which informs the database to open exclusively. With your version of the accde, you will not be able to access that code or change how the database opens.
Let's break this down (only because I finished all my work already...):
My next step is to split the database, create the front end and distribute. This is where i'm having problems. I created the original front end StockMaster2_fe.accde and placed it in the database folder on the F drive. Does every user get their own copy of the front end?
Yes
I copied and saved two more front ends (copy and paste in the same folder -> rename) namely StockMaster2_alan_fe and StockMaster2_ryan_fe and tested it. I told Ryan (who sits next to me) to find the front end named after him on the F drive and open it whilst i was in ...alan_fe. We both went to run macros at the same time but he was kicked out as it gave me exclusive access. What am i doing wrong?
Ensure your back end contains only tables. Access is a "client-centric" database, which means when a query is run it pulls all of the data over the pipe to your local computer, does what it does, and then sends it back. So, make sure the back end has only tables and all the other jazz (macros, queries, etc...) are in the front end. Also, the front end will contain links to the back-end tables. All of your queries/macros/etc.. will reference these links, and not the tables in the back-end DB directly.
Why is it not allowing multiple access?
Also, make sure your table-locking scheme is multi-user friendly. If you're doing table locking, it will cause errors. If you're doing record locking, it probably won't.
My problem is that due to strict administrator privileges i cannot download any software or access the command line, so anything that i do must be done in Access itself.
Shouldn't be a problem at all.
I am currently in the process of trying to launch a database that has a VB6 front end connected to an access 2000 database. On certain computers we are experiencing a problem where the data being pulled from the database does not show up or does not show up correctly.
The computers that work seem to have the same dao360.dll date modified in both the system 32 and microsoftshared/dao while the one that are not working do not have the same date modified.
Is this whats causing the error? How can I correct this? Or is it something else that is happening?
There shouldn't be two copies of the DLL on the system. It sounds like a poorly designed install of some application had been previously done on these systems. There is no telling what the full extent of this has been.
Packaging as an isolated application can insulate your programs from these kinds of bad installs that create DLL Hell. Sadly MDAC/DAC and related components are very difficult to isolate.
This is another reason to have moved to ADO back in 1998, if not in the time since then. While you can't isolate the ADO-related parts of MDAC/DAC any more than you can DAO, those libraries are now shipped as part of Windows. You don't need to deploy them and they are protected from bad installers by the increasingly better system file protection mechanisms in Windows.
However providing specific assistance will probably require a more specific and detailed description of what is going on than "does not show up or show up corectly."
I'd create a minimal test case using DAO to begin exploring where (and what) the problems really are. To begin with perhaps just a simple query displaying the returned rowset without data binding.
I suggest installing the latest version of MDAC and Jet. While Jet used to be a part of the MDAC, I'm pretty sure they dropped it into its own installl/update/service pack at this point. Perhaps start here: http://support.microsoft.com/kb/239114
We are building a webapp which is shipped to several client as a debian package. Each client runs his own server. But the update and support is done by us.
We make regular releases of the product, with a clean version number. Most of the users get an automatic update (by Puppet), some others don't.
We want to keep a trace of the version of the application (in order to allow the user to check the version in an "about" section, and for our support to help the user more accurately).
We plan to store the version of the code and the version of the base in our database, and to keep the info up to date automatically.
Is that a good idea ?
The other alternative we see is a file.
EDIT : The code and database schema are updated together. ( if we update to version x.y.z , both code and database go to x.y.z )
Using a table to track every change to a schema as described in this post is a good practice that I'd definitely suggest to follow.
For the application, if it is shipped independently of the database (which is not clear to me), I'd embed a file in the package (and thus not use the database to store the version of the web application).
If not and thus if both the application and the database versions are maintained in sync, then I'd just use the information stored in the database.
As a general rule, I would have both, DB version and application version. The problem here is how "private" is the database. If the database is "private" to the application, and user never modifies the schema then your initial solution is fine. In my experience, databases which accumulate several years of data stop being private, it means that users add a table or two and access data using some reporting tool; from that point on the database is not exclusively used by the application any more.
UPDATE
One more thing to consider is users (application) not being able to connect to the DB and calling for support. For this case it would be better to have version, etc.. stored on file system.
Assuming there are no compelling reasons to go with one approach or the other, I think I'd go with keeping them in the database.
I'd put them in both places. Then when running your about function you quickly check that they are both the same, and if they aren't you can display extra information about the version mismatch. If they're the same then you will only need to display one of them.
I've generally found users can do "clever" things like revert databases back to old versions by manually copying directories around "because they can" so defensively dealing with it is always a good idea.
I created a database for tracking metrics, with some automation tricks (email, .doc,.ppt presentations, etc) with a very large Main-table, and lots of forms/GUI. This is the first time I have ever I worried about an MDE/front-end for the thing. So if you would be so kind to answer a few questions, or offer any advice, it would be greatly appreciated (I would hate for all this work to not be utilized).
What is the first thing I need to do? It the 2000 version that must be converted to 03 to create the MDE, but does that get done before I use the database splitter?
Will the amount of objects in the database effect the ability to do this? I have something like 80 forms, 70 queries, 20+ macros, 12 tables, etc...but does the amount of objects prevent some of this from working well once the front end is there?
when i split the database, can I continue to work/make changes and such on the "back end", and have those changes directly effect the front end?
These may be some basic questions, but I don't know the answer so.....Thanks!
Here is my 2 ยข.
Question 1 - I have never used the database splitter as I feel I have more control doing it manually. If you do it manually you can do it to a version that does not have a database splitter. But if you do use the splitter then--yes--you will have to upgrade to a version that has a splitter before doing it.
To do it manually here are the steps.
Backup everything.
Create a copy of your file into the same directory. So if you have an MyApp.MDB create a copy into the same directory with a new name, such as MyAppDATA.mdb.
Open the new DATA file (MyAppDATA.mdb) and delete all of the objects EXCEPT the TABLES.
Open the App file (MyApp.mdb) and delete all of the tables.
Also in MyApp.mdb...go to the File/Get External Data/Link Tables menu to link the tables in MyAppDATA.mdb to MyApp.mdb. Select All and create the links.
That should do it. And if you screw up you made a backup...right?
A couple of tips and gotchas...be sure that you go to Tools/Options and that you are NOT showing System and Hidden tables. You just don't want to delete system tables from MyApp. Another way to do it is do NOT delete tables that start with MSys or USys.
Question 2 - Does not matter how many object you have. In fact you don't have that many objects anyway.
Question 3 - Yes...you will make backend changes in MyAppData.mdb and when you open MyApp.mdb those changes will auto-magically be there to see and query against etc. (In the query designer you may need to save/close/reopen to see new fields if you made the mod while in the query). The EXCEPTION to that is New Tables You will have to use the File/Get External Data/Link Tables option to create links to new tables.
One thing to remember (and that I hope you already realize) is that the one downside of splitting the database is that when you deploy the front end file that usually the relative path to the data will vary from machine to machine and there is no automatic re-linking of tables in access. If your target clients have full access you can always use Tools/Database Utilities/Linked Table Manager to refresh the links to the right location. If you can't do that then you will have to do one of the following:
1. Write code that does the automatic re-linking for you. Basically it will check the links...if invalid it will prompt the user for the data location (or look it up in an INI file) and re-link the tables.
2. Always deploy your app to the same location on all machines. If you have commercial visions for your application this won't work...I mention it for academic reasons. It might be doable for a limited deployment where you have a lot of control over file placement on each machine.
3. Put the Data file (MyAppDATA.mdb) onto a network share and link the table across the network using a drive mapping or UNC (\myserver\mydata\ApplicationData\MyAppData.mdb). The latter is preferred but both of them run the same risks as number two.
Seth
PS This answer assumes Access 2003.
PPS If you have commercial visions for your application then the table linking has got to be REALLY robust.
PPPS I agree with the commenter that you may want to take the plunge and do SQL if it is in your skill set.
One thing that hasn't been discussed, and that's the issue of whether the compile to MDE could fail. Basically, if your code compiles in your front-end MDB, it will convert to an MDE. But I've noticed that lots of people never compile.
Some hints for keeping your VBA code in good shape:
in VBE options, turn off COMPILE ON DEMAND.
add the COMPILE button to your standard VBE toolbar and USE IT OFTEN.
periodically, backup your MDB and decompile/recompile it.
Also, remember that you must keep the MDB source, as the VBA code is not editable in an MDE and not recoverable by any good method.
EDIT:
Steps for a decompile:
backup your MDB.
start an instance of Access with the /decompile commandline argument. For, instance, I have a shortcut on my deskstop that has this as the target:
"C:\Program Files\Microsoft Office\OFFICE11\MSACCESS.EXE" /decompile
having opened that instance of Access, open the MDB you want to decompile. You will see nothing happen. DO NOTHING FURTHER IN THIS INSTANCE OF ACCESS -- close this instance of Access (the reason for this is that Michael Kaplan, who knows a thing or two about this, recommended that you never do any work in an Access instance opened with the decompile switch because he said there was no guarantee that the Access application code executed under those circumstances in a way that was fully safe for all kinds of Access work).
open the just-decompiled MDB holding down the shift key (you want to be sure that startup routines don't run because that would likely recompile the product before you've finished your cleanup) and compact the MDB (holding down the shift key again).
open the code editor and compile the project (DEBUG -> COMPILE [db name] for those who haven't step #2 in my original compiling instructions at the top of the post before the edit).
compact the MDB (doesn't matter if you bypass startup, since it's already fully compiled).
Why so many steps?
Because the purpose of the decompile is to get rid of the compiled p-code in order to start afresh from the canonical VBA code. Following the steps above insures that you have completely cleared the data pages storing the compiled code before you recompile. The reason for this is that without the compact step after the decompile, under some very rare circumstances, the code can behave strangely. I can't imagine that the old discarded p-code is being used again, but there's something about the pointers between the canonical code and the compiled code that apparently doesn't get completely flushed by a decompile without a compact.
This would be a comment to Seth's answer, but my rep isn't high enough to comment yet.
Seth did a great job answering your questions, I just wanted to add a bit more to part #1 about using the Database Splitter. The Database Splitter in the Tools menu works fine. Doing it manually is alright too, but it's a whole lot faster and easier to use the Database Splitter. I've used it a dozen times and never encountered any issues after using it.
http://www.databasedev.co.uk/split_a_database.html has a decent page about some of the pros, cons of splitting your database.
http://www.accessmvp.com/TWickerath/articles/multiuser.htm also has some good info when dealing with a split database in a multi-user environment.
Seth gave you a very good answer. But I'll add a few comments.
The number of objects only becomes relevant when you get close to about 1000 forms, reports and modules which have code. There's a limit about there. If you do get that message when trying to make an MDE then you almost certainly have a code error and need to compile to find the error
Another resource is "Splitting your app into a front end and back end Tips"
See the Auto FE Updater downloads page to make the process of distributing new FEs relatively painless.. The utility also supports Terminal Server/Citrix quite nicely.