Please, give me the most serious arguments against this.
Application directly opens a connection to ms sql server, directly executes queries.
So what I'd like to ask:
1) Why it is wrong when the number of users can be up to 1000 executing huge queries?
2) What serious problems can that cause?
3) What should I do?:)
Arguments, the most serious arguments against this kind of implementation!
One of the things to consider is how the queries are done. 1000 queries against a SQL Server DB might be manageable, but 1000 Access queries in which the table is locked, or which are actually joins or views, could use dramatically more memory. It really depends on how the application is written. Some Access apps open a recordset and page through the records one at a time, or fetch a few dozen and work on those, but sometimes Access grabs the whole recordset, for example to allow users to page through data. And I have seen Access lock a set of tables to allow editing of them. That would be bad in your scenario.
Of course, I wholeheartedly agree with the "10 years out of support" issue. That is a guaranteed problem. Mine is only a possibility. And you should probably update SQL Server to a current version also, for the same reason.
What about:
The version of access 97 is totally outdated and wont get any updates, has a crappy look, crappy functionality and in general - IF it requires rework - should be updated.
Problems? You run on a 10 year old out of support platform. What problem can that cause? Well - what about limited support?
Upgrade at least to 2007, better 2010 (coming in a couple of weeks) when you have a momnent time. I personally dispise access based applications (crappy architecture to start with etc.), but if there is one, the update to access 2010 is possible the most painless way to go.
Access 2003 or 2007 would be just fine for the scenario as long as you had an Access developer who was up to speed on how to develop for client/server with large user populations.
Access 97 is still an awfully nice version of Access. I think it's the best version ever produced.
But it is out of support and predates the alteration of default permissions in Windows implemented with the release of Windows 2000. This means that it has some problems in installing with its default permissions (it expects write access to its application folders and registry keys). An installation script can easily alter these appropriately, but you're still left with problems in certain contexts, like trying to run it in Windows Terminal Server/Citrix, where it very often just completely breaks.
I would like to hear an explanation of exactly why someone would choose A97 for new development. Of course, I may be misinterpreting. You may be asking about an existing app, in which case I'd go with "if it ain't broke, don't fix it," and then ask exactly what it is that is perceived as "broken." Those things can be fixed, though it's unlikely that simply upgrading from A97 to something more recent is going to do the job.
I’m currently nearly finished with a brand new application written in access 97 that stores its data in SQL server 2008. As has been said many times before the access/SQL server combination really works great.
Inline with my other applications it is completely unbound using ADO to get the data from the server. I wont drag up that debate again here but it is something you really want to look into as it can offer some great benefits.
Most of the SQL server guide you will find will ask you to check that you have the correct indexes and try to identify the slowest running parts of the system or the ones that get called a lot and then look at making them faster. That might cause you to make a covering index or to denormalise the data in someway.
Generally what is good practice for JET also works well for SQL server, make a good table schema with a good clustered index choice and good supporting indexes and you are 95% of the way there
Related
Our company is upgrading all work computers soon and no longer supporting MS Access. Unfortunately, a lot of important database is stored in a plethora of Access databases with many differing styles of interfaces. Storing it all on a database server is out of the question. What is a good portable (non-server) database system that I can use?
The one I'm leaning toward is SQLite, but I'd also like to be able to write interfaces to query the data. If I use SQLite, what is a good way to write a query interface that will work on a lot of Windows machines natively?
EDIT: Data migration will not be a problem. I'm more worried about interface migration. What is a good way to write a query interface for one of these portable database systems?
EDIT2: It seems that there's some confusion as to what I mean by "query interface". I don't need a complete query system. I'm simply looking to create a simple frontend through which I can search the Database by table and by fields.
Judging by the title of your question, you are concerned about what database (i.e. data container) should be used in place of Microsoft Access. However, viewing your question and the ensuing answers and comments, your greater concern is actually what to use to design the Application/user interface, what you are referring to as the "query interface".
Here's a couple things you need to realize:
1) SELECT queries allow you to extract data from a database. However, the data has to get into the database somehow. At no point have you specified whether or not your so-called "query interface" is also used for data entry. If it is in fact used for data entry, as I suspect it is, then you should concern yourself with how your going to design your "application", not your "query interface". Data entry often requires a certain amount of guidance and logic that is defined outside of the database. This logic includes (but is not limited to) things like validation rules, input masks, parent child relationships that are enforced by the GUI design. This is essentially an application, not merely a "query interface". Applications are usually designed to make data entry easier than having the user enter data directly into the tables. But even here you must realize that ultimately a user can't even enter data directly into a table without some type of application GUI, whether that GUI is something you've designed or not.
2) Microsoft Access is a Rapid Application Development (RAD) tool that allows you to quickly and easily design and save queries, forms, and reports. It appears to me that you're real question is, What RAD tool other than Microsoft Access can I use to develop queries and forms for viewing and entering data in small desktop databases? And what database would you recommend we use together with the RAD tool you're recommending?
Assuming I've properly defined your actual question, allow me to give my own viewpoint on this question. First, as has already been pointed out in another answer, as long as the clients are running MS Windows, you don't really need to move away from using Access/Jet/ACC as your database (data container, the part that holds the tables). As long as MDAC is installed an Access database should be "machine readable".
It seems to me the more important question here is what RAD tool should you use in place of Microsoft Access? After you answer this question perhaps it will help you answer the first question, of what database should be used. In answer to this question, let's be honest. While Microsoft Access has it's shortcomings, you probably won't find any other RAD tool that allows you to so easily create Forms for data entry. FileMaker Pro is one of the only competing products that I know of.
Yes, you could use Visual Studio .Net to create .exe runtimes. These runtimes can include forms for viewing and entering data as well as reports. I think you'll find that the learning curve is pretty major, especially if you are not yet familiar with ADO.Net which is very different from DAO or ADO Classic. If you want to give your users ways to create their own queries/filters or reports you'll have to design this functionality into your GUI since Visual Studio doesn't give you the easy wizards and design tools you'll find in Microsoft Access. While Visual Studio is far more powerful than MS Access, you need to realize that the development time for even the simplest of applications is probably going to be much higher, especially when you are first learning.
Are there any other RAD tools you could possibly use? I know little if anything about the different design tools listed here but this might be a good place for you to start: http://en.wikipedia.org/wiki/List_of_rapid_application_development_tools#Desktop_Rapid_Application_Development_Tools
SQLite is a great option and will extend your reach to many platforms beyond Windows (iOS, OSX, Android, etc.). I recommend this. If you want to keep using Microsoft products, SQL Server Express or Compact Edition is another possibility.
Another solution, depending on what you are doing with these databases, would be Microsoft SQL Server Compact Edition which does not require an installer.
No matter what database you choose, you are going to be faced with migrating your queries to a different dialect of the SQL language (the actual syntax of your queries). They all have their quirks and features (and missing features). That is just the nature of the beast. It should be noted that you can still access a MS Access database in code without requiring the installation of MS Access.
It appears that the nature of the question has changed dramatically since it was originally posted. The question has apparently morphed into one about finding an user interface development environment that has similar features to Access. This is obviously an entirely different question than finding a replacement for Access (or specifically Jet for those anal retentives in the audience) as a database engine.
There are many alternatives and it depends greatly on whether you wish to continue with a Windows application or whether you wish to move to a browser based interface. Given various comments, it sounds like you may still want a Windows based solution. A couple of solutions you might investigate:
.NET Windows Forms - The .NET environment is incredibly powerful and provides for very rapid development. IMO, as rapid as Access if you know what you are doing and far more powerful. However, with those additional capabilities comes additional complexity. No question that jumping into Windows Forms from pure Access development will be daunting but rewarding.
Another solution, which I admit to not having tested myself, but looks promising is Kexi + SQLite which is geared as an open source replacement for Access.
If you considered changing gears and switching to a browser based approach, there are again many choices. PHP, ASP.NET (MVC and not), Ruby and so on. As with Windows Forms, switching to browser based development from Access development will be a daunting change but also rewarding.
Of course, if the PHB are eliminating Access as a cost cutting move, you could split the existing Access databases to Front-end/backend applications, migrate the backends to SQL Server Express edition (free) and have the users use the MS Access run-time (also free) You, the developer, are the only one who actually needs a paid-for full version of Access.
This response comes long after the question was posted--but Google still turns it up near the top of results for 'replace ms access'
You should include MySQL and PostgreSQL on your list of the potential replacements. MySQL supports AUTO_INCREMENT columns, so it might be a better replacement for the Microsoft databases. Also, Microsoft SQL Server Express might be not a bad option. I migrated from using MS Access databases to using MS SQL Server Express in my apps when I was using Microsoft technologies about 10-12 years ago.
I went for a job interview this morning, and one of the scenarios that the IT manager (a former programmer) told me about was the following .... If anyone could give me any pointers that I can email him pointers to tomorrow (Wednesday 22nd) it may just help tip his decision in my direction. So there's beer in it if you answer a relevent answer, and I get the job.
Old systems using Access 2 databases. These systems are not due to be updated any time soon.
New systems need access to that data, so each night he exports information using SSIS. However, he needs to also write data back, and more often than just overnight.
However, when he connects to the database, using ODBC connections I think, he says that the app (SSIS) opens the tables / database exclusively, even if he selects the option NOT to open it exclusively.
Any ideas, suggestions or comments ?
Could it be that the Access db itself is set up to open exclusively. Gosh it's been about a million years since I used Access 2.
Another possibility to fix is to consider making the SQl server tables that mimic the access tables and making them linked tables in access and using them instead of access. I can't remember if you can do this with Access 2 or not. If you can do this, then you will be making changes directly to the sql servver tables and not locking them up in Access 2. It's at least something to try. The use of linked tables should't break anything in Access if they have the same names and all tables havea primary key. ANd then you can performance tune as well if there are problems.
I'm throwing out ideas here, up to you to research the feasibilty before sending them on. But honestly, do you really really want to work for an organization that still uses Access2? If they haven't upgraded that, what else are they years out of date on? Access2 came out in 1993. So they haven't upgraded it in 17 years, scary stuff.
This is something I would like to see while doing my day today programming works, But I've never seen such application yet. You input is highly appreciated.
Lets say we have an application that needs MSSQL server as DBMS. And suppose you just need to install it and do something. (i.e You are not going to deply it in production servers etc.)
In such a case it might be an overhead, of installing MSSQL first. I am suggesing something like a software bridge that can use another DBMS to store data. In other words the application "sees" an MSSQL instance but underneath that it might be Access. The bridge sholud do some sort of conversion.
Another example : You have MSSQL but a certain application needs Oracle. You have to purchase Oracle then. But with a something like a bridge, You can put information into your MSSQL DBMS. The bridge listens to port 1521 like Oracle so application "Thinks" there is an oracle installation.
Is it an idea that cannot be implemented?
Are there any such applications?
If so what are they?
Thanks... :)
Adding a Clarification : The application might be from a third party. You don't have any knowledge on internal architecture of that. you just know it uses a certain DBMS. I am trying to use a different DBMS other than the third party software needs.
Application usually don't depend on a specific database server, OR they depend on it for a reason.
If an application asks for oracle, or sql server, or whatever, it's because it relies on the implementation details of this specific vendor to run its SQL, its stored procedures, etc. There's no way you could emulate that with an access database, for example...
If your application just needs to run some very simple SQL (ie basic insert/select statements), it probably uses a standard driver (odbc, ado, etc.), and those drivers can accommodate every major sql database engines. In my experience, "simple applications" don't ask for a specific database vendor.
This is the problem that ODBC was supposed to solve :-) .
But in response to your questions:
Is it an idea that cannot be implemented?
It can be implemented.
It would be tedious and thankless work, and you would have a very limited audiance. In my opinion it's not worth doing.
Are there any such applications?
None that I know of.
If so what are they?
None that I know of.
......
Bringing in Chandrasekar's note in the comments section:
Have a look in a super user's perspective... He has a nice application but he can't use it without some DBMS. But still he is not a programmer to do something. So they need such a product
I agree it has applications, but it has a very limited audiance :) .
What you're proposing is something like the firefox plugin 'ietab', Only you won't have ie installed... so instead of embedding ie, you would need to entirely re-implement ie using firefox's rendering window.
Just my opinion : that's too much effort... It's simpler to just install a second database.
If this application uses ADO to connect to SQL Server and you can modify the connection string, then it's quite easy to use a different database: change the connection string! However, the other database must be able to support all features of SQL Server. Besides, the software was never tested on another database so the application might Crash & Burn.
If you can't change the connection string, or the application doesn't use ADO, things are more complicated and very close to impossible.
I've worked in the past on a project that needed to be reasonable database-independent. The database had to support stored procedures but there weren't any other restrictions. By default, we tried to support both SQL Server and Oracle. (We also supported Interbase but never advertised this.) While we did manage to keep it mostly database-independent, we did have to work around quite a few minor issues. Especially joins in our queries had some nasty problems which we just solved by adding more logic to stored procedures.
"This is the problem that ODBC was supposed to solve :-) ."
And it is the very same problem that SQL was intended to solve too.
It seems to me that the reason why this problem exists is that the world seemingly fails to agree sufficiently on what the data manipulation language/interface ought to look like.
I suspect that if this were solvable, it would already have been done.
The closest I've heard is EnterpriseDB where they have built a layer on top of Postgres so it looks more like Oracle.
But remember these databases have features covered by patents and copyright so there's a limit on how closely a competitor product can imitate the real thing.
It would probably be easier to imitate 'down' than up. For example, MS-Access wouldn't be able to imitate much of the functionality for Oracle or SQL Server, whereas there's a much better chance of SQL Server imitating a simpler DB like Access.
Applications usually DO depend on a specific database server. Every database implements things slightly differently - even MSSQL and Sybase, which have a common ancestor.
Any bridge, however well it attempts to abstract the differences, would leave some exposed. These would be likely to create subtle bugs in the application, which might appear initially to work, but then fail, or worse, corrupt data.
Moreover, the application vendor would not support you in such a case - they'd simply say they don't support that use case, and you should remove the bridge and install a proper instance of whatever database it was intended for.
In short, I don't think it's worth the risk of the application malfunctioning subtly, and being left without support, even if the application isn't especially important. If you dislike the underlying database the application uses, choose a different application.
I am having a real problem at work with a highly ingrained developer obsessed with ms access. Users moan about random crashes, locking errors, freeze's, the application slowing down (especially in 2007) but seem to be very resistant to moving it. Most of the time they blame the computer and can't be convinced it's the fact its a mdb sat on a network drive and nothing to do with the hardware sat in front of them which is brand new.
There is a front end vb program hanging off it but I don't think it would take more than a couple of weeks to adjust, infact I would probably re-write it as it has year on year messy code from a previous developer.
What are my best arguments to convince them we need to move it?
Does anyone else have similar problems with developers stuck in their ways?
how about the random, crashes, locking errors, freeze's, slow downs (sic).
A quick search on the web finds some useful materials:
Best Practices When Using Microsoft Office Access 2003 in a Multi-user Environment - if the changes here can't be implemented, or would effectively take a rewrite, then that is good ammunition for doing it right.
SQL Server vs MS Access - pay special attention to feature limits. Eg You can only have 32,000 objects in an access DB. Caveat: though it says 255 concurrent users, and that is probably a technical limitation, the practical limitation is really MUCH lower.
It's hard to convince people that are not willing to learn and are not open to new ideas. You can go on about speed issues, concurrency issues, security problems.. but ultimately, some people will just never listen. Go over their heads. Rewrite it in tools from this decade and show them up. Refuse to be involved with the project and further. I don't know what the political situation is, but technically, MS access is wrong for what you are doing, from what you've described.
come in on a weekend, copy the database to sql server, change the app's connect-strings to sql server, retest the application, then uninstall ms-access...everywhere.
then don't say anything about it, let him think that the problems 'fixed themselves' and that the users are still using ms-access
To me it depends on how many concurrent users you have and how big the database is. If you have more than 5 concurrent users then you should be thinking about a database server. The network traffic starts to get out of hand and with each concurrent user you add it just gets worse.
I have created reliable access based systems for years. If you are having random crashes, locking issues, and slow downs then you aren't doing something right. I typically will have an mda local with the mdb on the network when creating an app in access. To have good performance it's key to have the proper indexes and queries optimized for getting just the data you need. Whether using a separate app, access, or some app running against sql server you need to actively handle record locking properly. You can't just blindly let access lock your records.
Forget the arguments about DB Size, it is an uninformed reason to shift to a client-server platform in 90% of the cases I hear it brought up.
Your best arguments are based on features explained at a low tech level:
(1) You can backup and perform maintenance on the DB without kicking out the users (which introduces costly downtime).
(2) Faster recovery if data is accidentally deleted/mangled or corrupted. Again, less risk and less downtime. This is always a good foundation for a business case.
(3) If (and only if) you anticipate the need to scale quite a bit, the upgrade will better allow that.
(4) If you need to run automated jobs/updates, SQL can do this much more elegantly.
Remember the contra-indications for SQL, it is easy to get on your technical high-horse about this platform versus that, but you have to balance the benefits against the costs.
SQL is a Helluva lot more expensive to maintain as it requires dedicated hardware, expensive licenses (Server OS and DB) and usually at least a part time DBA that is going to cost you a bare minimum of $75K (if you get luck AND work out of Podunk Iowa).
The best possible advice I can give you is to make sure that you have a good attitude and are known as someone who does quality work and gets things done. It sounds like you don't have any control in the situation so what you need is influence.
Find a way to solve a problem (probably a different one that is less threatening to the people involved) in the way you are suggesting. Make it work blindingly fast and flawlessly. Make it work so well that people start asking for you when they need something done. Get it done quickly, which you should be able to do because you'll be using the right tools for the job.
Be a good person to work with, not the PITA that knows how everyone else should write their code. Be able to give an answer for what you might do differently and why, but don't automatically assume that your ideas are always the best. Maybe there are trade-offs that you don't know about -- no money in the budget for the extra CALs, we have this other app that needs to be done first. This doesn't sound like your situation, but looking for opportunities to understand before making constructive criticisms can go a long way to helping people be receptive.
The other thing is that this probably has nothing to do with the technical aspects of the situation and everything to do with the insecurities of the other developer. "This is all I know. If we change it, I won't understand it and then where will I be." Look for ways to help the other guy grow -- when he's having a problem, find resources that will help him develop good technical solutions. Suggest that everyone in your department get some training in new technologies. Who knows, one good SQL Server course and the guy could become the SQL Server evangelist in the organization because now THAT'S what he knows.
Lastly, know when to cut your losses, so to speak. If you find that you're not able to do anything about the situation, don't add to the complaining. Move on to something that you can control and do it as well as you can. Maybe in the future you'll be in a position that you do have control or influence in the situation and can do something about it. If you find that you're in a company that's more dysfunctional than most, find a way to move on to a place where the environment is better.
It is possible, and actually fairly easy, to convert an Access database to having the tables/views in SQL Server while still using the Access app as a front-end.
From there, your Access-obsessed developer can still have fun with all that VBA code. Meanwhile, on the back-end, you add indexes and such to speed everything up. Maybe someday you get lucky, and he asks about stored procedures. Then, the app is just a front-end, and who cares what it's written in? Your data is safe in SQL Server.
It is possible for you to do this yourself, but just leave the production app ALOOOOOOOOOOOONE. Take a copy, and convert that copy. Then, host it for a couple of users to TEST drive .. make your version of the Access app show "TEST APP" in big red letters. If your developer asks what you're doing, you can say the truth -- you are testing to see if converting only the tables/views might be of some help to the overall app.
This way, you get the best of both worlds, keep your developer happy, make the users happier (hopefully), and if you play it right, your bosses will know that you handled a knotty personnel issue with your technological prowess and your maturity.
I once had similar problems with someone I would not hesistate to call a complete idiot.
It was not possible to convince them of the issues with access. In the end it was easier to force the issue than do it "nicely", cruel to be kind.
If they resist then you can always go above their head. Management must be aware of crashes and stability related issues. Present a plan to them to improve stability and they are likely to at least listen. They will probably then want a meeting with all developers to discuss so go into it armed with plenty of ammo.
More than "How to convince them", let's talk about "How to do it without anybody noticing"!
First of all I advice you not to mix together the code optimisation issue and the SQL server one. Do not give users a chance to complain about SQL while bugs are related to something else.
If your code is really unbearable, rewrite the app before switching to SQL, keeping in mind the following points to make the final transition to SQL Server completely transparent for final users.
This is what we did 18 months ago, and I am sure we still have users thinking our database is Access:
Export current access database to SQL through available Wizard in access for testing purposes (many problems might occur, and you could need another tool such as the one proposed here).
Create a unique connection object at the application level, so that you can freely switch from Access to SQL at any time (at development level, you can even add an input box at startup to ask which connection to use). We chose an ADODB connection object, but it will also work with ODBC connection.
In case you use SQL syntax to update tables, make sure that all SELECTs, INSERTs, UPDATEs and DELETEs make use of this connection. In case you use recordset, make sure that all of them use this connection at opening time.
When needed, update all connexion specific code by adding a "SELECT CASE" type_Of_TheConnexion options
Switch to SQL connection ..and debug till you're done!
The problems you will find are mainly linked to SQL syntax, where MSSQL uses ' instead of " and # as separators. Date format is also an issue, where standard SQL format is 'YYYYMMDD' while MS-Access format depends on computer locals (beware of conversions from date to string!) and is stored as "YYYY-MM-DD" (if I remember ...). Boolean in SQL are 0 and 1, while they are True/False or 0/-1 in Access ...
Test, update code, and when you are ok, make a new data transfer, lock your app on the SQL connection, and distribute a new runtime.
It depends on the type of application and data load of your database but Access is quite efficient, even over the network.
Depending on the amount of data your users deal with you could easily scale up to a 100 users on a network just using a from and back-end Access database.
Looks like in your case a rewrite may be in order. If your application is data-centric if doesn't make much sense to develop it in VB6: the tools given by Access are much better than anything you'd be able to make, especially when considering Access 2007.
Upsizing to SQL Server is only really required if you're getting into issues of:
Security:
you need to make sure that only the rights users can access data. You can do your own security in Access, but it's never going to be as strong as SQL Server.
Scalability:
you're dealing with lots of data and complex queries or a lot of users and it would be better to have dedicated hardware to handle the load for the clients. The issue with this though is that while removing the pressure from the less-capable clients machines, you're adding a lot more to the server.
Integrity:
With the back-end database being just a file that needs R/W access for all connected clients, there's always the possibility that someone is going to do something bad or that a client may crash and leave the database corrupted.
If your number of users is average (I'd say 30), then there's probably no real need to upscale:
Use MS Access 2007 to develop your application, then just use the MS Access 2007 Runtime (it's free!) on all client machines to get a more modern user interface (uses the Ribbon and has lots of UI enhancements over previous versions).
You can't be the cheapness of that solution : you only need full retail version of MS Access and all the rest is free, regardess of the number of users!
Don't think that moving to SQL Server is going to improve performance of your queries: MS Access often does a better job of optimizing the queries for you (it knows what needs to be displayed and does lots of caching and optimization).
Make sure you only edit small amounts of data at any one time (don't use dynaset queries just to display vast amounts of data in a datasheet; use a snapshot instead and open a detail form that only contains the data to edit when necessary.
Cache complex queries locally.
Built some caching mechanism that leaves a copy of the results of a complex query on the local machine. The gain in performance is pretty amazing and if the query doens't change much (for instance a log of stock operations) you can just persist the complex/big query locally and append new records as necessary.
There is so much more to say.
Bottom line is: you may be looking at a rewrite, but don't dismiss Access as the solution because your current application was poorly written.
Try bechmarking and showing the stats to him
Making people change can sometimes be a real pain in the butt.
I would have to say the main argument would have stability and speed, but of course like you have said they already know this a still won't move.
Another thing to try would be to show them the power of LINQ to SQL and how much cleaner it would make your application. Like Daniel Silveira said you could try and throw a couple of stats there way and see if they are convinced.
We have a app build using MS access as a back end and I can't wait till we get our new SQL server so I can move everything to that.
You could show him the perf results comparing the two, but if he's really set in his ways and refuses to change, there isn't much you can do except force him somehow.
If you're his boss then just force him to change it to use SQL. If not, then convince your boss to force the change by showing him the perf results and explain it'll fix the issues you're having.
Errr, leave the team? You seem to be working with the totally wrong set of people. Now, if the team IS your company, then you are working with the wrong company.
Of course once you leave the company, you could tell your clients that you could solve the network problems on their own and make them leave the company as well. Then give them an improved system that works on SQL Server Express.
I need a database that could be stored network drive and would allow multiple users (up to 20) to use it without any server software.
I'm considering MS Access or Berkeley DB.
Can you share your experience with file databases?
Which one did you use, did you have any problems with it?
I really don't think that file-based databases can scale past half a dozen users. The last time I had an Access database (admittedly this was quite a while ago) I had to work really hard to get it to work for 8-9 people.
It is really much easier to install Ubuntu on an old junk computer with PostgreSQL or MySQL. That's what I had to do even when I kept my Access front-end.
I would suggest SQLite because the entire database is stored in a single file, and it quite safely handles multiple users accessing it at the same time. There are several different libraries that you can use for your client application and there is no server software needed.
One of the strengths is that it mimics SQL servers so closely that if you need to convert from using a database file to a full-fledged SQL Server, most of your queries in your client won't need to change. You'll just need to migrate the data over to the new server database (which I wouldn't be surprised if there are programs to convert SQLite databases to MySQL databases, for example.)
Beware of any file based database, they are all likely to have the same problems. Your situation really calls for a Client/Server solution.
From SQLite FAQ
A good rule of thumb is that you
should avoid using SQLite in
situations where the same database
will be accessed simultaneously from
many computers over a network
filesystem.
http://www.sqlite.org/whentouse.html
Access can be a bitch. Ive been in the position where i had to go around and tell 20-50 people to close access so I could go to "design mode" to change the design of the forms and maybe a column. No fun at all. (Old access, and it might just be a bad setup)
Ayende was recently trying to make a similar decision, and tried a bunch of so-called embedded databases. Hopefully his observations can help you.
I have been using Access for some time and in a variety of situations, including on-line. I have found that Access works well if it is properly set up according to the guidelines. One advantage of Access is that it includes everything in one package: Forms, Query Building, Reports, Database Management, and VBA. In addition, it works well with all other Office applications. The Access 2007 runtime can be obtained free from here, which makes distribution less expensive. Access is certainly unsuitable for large operations, but it should be quite suitable for twenty users. EDIT: Microsoft puts the number of concurrent users at 255.
Can Access be set up to support 10-20 users? Yes. It, as well as all file-based databases use the file system for locking and concurrency control, however. And, Access data files are more susceptible to database corruption than are database servers. And, while you can set it up for this, you MUST, as David Fenton mentions above, follow best practices, if you want to end up with a reliable system.
Personally, I find that, given the hoops that you need to jump through to ensure that an Access solution is reasonably trouble-free, it is much less trouble to implement an instance of MSDE/SQL Server Express, or postgreSql.
Berkeley DB supports a high degree of concurrency (far more then 20), but it does so primarily by utilizing shared memory and mutexes (possibly even replication) - facilities that do not work well when BDB is deployed as a file stored on a network drive.
In order to take advantage of DBD concurrency capabilities you will have to build an application around it.
The original question makes no sense to me, in that the options don't belong together. BerkeleyDB is a database engine only, while Access is an application development tool that ships with a default file-based (i.e., non-server) database engine (Jet). By virtue of putting Access with Berkeley, it seems obvious that what is needed is only a database engine, and no application at all, but how end users use Berkeley DB without a front end, I don't know (I've only used it from the command line).
Those who cannot run a Jet MDB with 20 simultaneous users are simply not competent to be giving advice on using Jet as a data store. It is completely doable as long as best practices are followed. I would recommend in addition to Microsoft's Best Practices web page, Tony Toews's Best Practices, and Tony's Corruption FAQ (i.e., things you want to avoid doing in order to have a stable application).
I strongly doubt that the original questioner is building no front end application, but since he doesn't indicate what kind of front end is involved, it's hard to recommend a back end that will go with it. Access has the advantage of giving you both parts of the equation, and when used properly, is perfectly reliable for multiple users.