I am working on migrating a MS Access Database over to a newer SQL platform.
But, with all of the users who are currently using it, we're migrating slowly/carefully.
The first step is that we are re-writing the VBA code into C#, which is then deployed in a .dll along with the database.
Now, the VBA code calls into the C# to do the business logic, then the VBA continues to do the displays/UI, while Access still hosts the database.
The problem comes in that I have a report that is being run after the business logic from the C# in one place, and apparently MS Access has a cache, which clears every 5 seconds. So, the transaction that occurs in the C# code writes to the database, but the VBA code is still using the cache. This is causing errors, as the records added to the database (which the VBA report is trying to report on) don't exist in the cache yet...
I'm guessing that the C# .dll must be getting treated as a "second connection" to the MS Access database, which is what seems to typically cause this error in my searches (thinks that one process is writing, and the other is reading).
Since the cache is cleared out every 5 seconds, we can just put the process to sleep, and wake it up after 5 seconds, and then run the report, but that's pretty terrible for an end user.
And, making things difficult, the cache seems like it only gets used in the deployed version (so, when running from source / in debug mode, the error never happens).
Doing some searches, there seems to be plenty of people who have said "just refresh the cache." But, the question is: within VBA, how do you refresh the cache?
Any advice would be welcome.
Thanks
I've been fighting the same issue for years as I write a lot of tools around an old Powerbuilder application that has an Access MDB back end.
The cache does exist and it is VERY real. When data is inserted on a different connection than it is queried on, the cache can be directly observed and measured. It was also documented by Microsoft before they blackholed a bunch of their old articles...
Microsoft Jet has a read-cache that is updated every PageTimeout milliseconds (default is 5000ms = 5 seconds). It also has a lazy-write mechanism that operates on a separate thread to main processing and thus writes changes to disk asynchronously. These two mechanisms help boost performance, but in certain situations that require high concurrency, they may create problems.
I've found a couple workarounds that are not the best, but somewhat make due until I find something better or can re-write the app with a better back end database.
The seemingly best answer I've found (that may actually work for you since you say you need VBA) is to use JRO.RefreshCache. I've been trying to figure out how to implement this using C# or VB.net without any luck. Below is a link to a code example where you execute the RefreshCache method on your 2nd connection that needs to pull the data. I have not tested this myself.
https://documentation.help/MSJRO/jrmthrefreshcachex.htm
A workaround I've found that will deliver the query results within 500ms to 1000ms of insert time (instead of anywhere between 500 and 5000 ms - or more):
Use System.Data.ODBC instead of OleDB, with connection string: Driver={Microsoft Access Driver (*.mdb, *.accdb)};Dbq=;
If someone knows how to use the JRO.RefreshCache method with OLEDB and C# or VB.net, I'd be forever grateful. I believe the issue is it's looking for an ADO connection to be passed in, not an OLEDB connection.
I not aware of ANY suggesting that some 5 second cache exits? Where did this idea come from????
Furthermore, if you have 5 users, then you not going to be able to update their cache, are you?
In other words, the issue of some cache for one user still not going to solve or work with mutli-users anyway, is it?
The simple matter is if you load up a form with 100 reocrds, and then other users are ALSO working on that 100 rows, then all users will not see other changes until such time you tell access to re-load the form.
You can do this with a me.Refresh in the form, and then it will show changes made by other users (or even your c# code!!!).
However, that not really the soluion here.
How does near EVERY system deal with this issue?
Answer:
You don't, you "design" the software to take the user work flow into account.
So, in place of loading up a form with 100 rows of data? (which you should not, unless SUPER DUPER reason exists for doing that).
The you provide a UI in which the user FIRST searches for whatever it is they want to work on.
In other words, say you just booked a user on a tour. Now, they call the office back, and want to change some details of that tour. But, a different tour staff might pick up the phone. So, now a 2nd user opens the tour?
So, you solve that issue by NOT loading all the tours into that form in the first place.
you provide a search screen, so they can search for the user, find the user, maybe type in a invoice number or whatever.
You display the results in a pick list, and then launch the form to the ONE record (and perhaps detail records from child tables).
So there no concpet of a cache in Access anymore then there is in c#.
However, if you load up a datatable in c#, and then display that data?
Well, what about the other users on that system. They will not see changes to that data ANY MORE then the current access form.
So, if you want to update some data in c#? Then fine, but you need/want to do two things:
First, before you call any c# code that may update the current form reocrd? You need to FORCE a data save of that current record BEFORE you call any code, be it VBA code, or c# code that going to update that current reocrd the user is working on.
You can in Access save the current reocrd in MANY different ways, but the typical approach is:
' single record save - current record
if me.dirty then me.dirty = false
' VBA or c# code goes here.
' optional refresh the current form to reflect changes
me.Refresh
So, in most cases, it is the "design" of your software that will solve this issue.
For example, in the tour example, or in fact ANY system, the user can't work, can't update, and can't do their job UNLESS they first find/search and have a means to bring up that form + record data in the first place.
So, ANY typical good design will:
Ask the user for that name, invoce number or whatever.
Display the results of the search, and THEN allow the user to pick the record/data to work on. When they are done, they close that form and are RIGHT BACK to the search form to do battle with the next customer or task or phone call or whatever.
So, a search form might look like this:
In above, I typed in smi, and then displayed a pick list.
The user can further type in say part of the first name, and thus now get this:
So, maybe they type in a invoice number, customer number, booking number or whatever.
So, you display the results, and then they can select the row or "thing" to work on.
thus, we click on the row (or above glasses button), and then jump to the ONE record.
so, the user does whatever they have to do with the customer. Now, when done, they close the ONE thing, the ONE main reocrd.
This not only saves the data (so others in the office can now use that booking data), but it also means the data is saved. and they are NOW right back at the search screen, ready to do battle with the next customer.
So, not only does this mean we have a VERY bandwith friednly design (we only pull the one main reocrd into that form), but it also is better for work flow.
The Access form's cache thus becomes a non issue, since we only dealing with the one record.
And as I pointed out, if the system is multi-user, then you NOT going to be able to udpate and deal with multiple users cached data anyway, are you?
Think of ANY system you EVER used from a software point of view.
When you use google, does it download the WHOLE internet, and then you use ctrl-f to search megs and megs of data in the browser?
Nope!
you search first, get a list of that search, and THEN pick one!!
And when that list is display, maybe others on the internet are udpateing, and add new data - but if that was cached in your browser, then it would not work!!!
And same goes for a desktop accounting system. You don't load up all accounts, and THEN have the user go ctrl-f to search all the data. You search for the customer, invoice number and PICK ONE to work on.
And it does not make sense to load up a form with 1000 customers, and then go ctrl-f to find that customer. Same goes for a instant banking machine. It does not download ALL customers and THEN let you search. It asks you FIRST to get what you need. So, be it browser based, desktop based, or JUST ABOUT ANY software you use?
You quite much elminate the cache issue, since not pre-loading boatloads of data, but asking and letting the user search for the data they need.
So, in regards to the Access form data and cache?
If you are on a form, and call VBA code, or c# code or whatever?
If that code update the current form, you have NO MORE OR LESS of a issue when calling VBA code, or c# code!!!! If that code updates the current form, and the reocrd is dirty (has pending edits), then you get that message about the current form's reocrd having been udpated by another user!!!
So, your cache issue does NOT IN ANY WAY exist MORE or LESS as a issue in typical Access software.
As a genreal rule, if you are on a form with pending edits, and say want to pop up some form to edit releated data?
You have to ensure that pending edits are SAVED before you launch an form that can edit the same data, or run code that can/may edit that data.
As a result, ZERO cache issues should exist, and they no more or no less exist when calling sql or VBA update code in a form then calling some c# code from that form.
So, write the pending update for that form.
Then run your VBA, SQL, or c# code.
And then do a me.Refresh to display any changes made by those external routines.
there is no documetjion, or ANY article I can find that suggests some kind of 5 seocnd cache or update - it is a urban myth, and your software challenge here in regards to use c# or VBA, or even SQL server stored procedures?
They are all the same issue, and I dare say that often access is used as a front end to SQL server, and ALL OF the SAME issues exist when using SQL server with ms-access.
I have a database that runs compliance reports, In this there are 13 fields that need to pull X number of records during a query, based on if we're past compliance date, or before compliance date.
I've been unable to come up with successful code to properly filter the database, not for a lack of trying, people here were quite adept and had good suggestions on previous answers, but alas none of them provided the desired results.
What I would like to do is have the end user click a button on the form, and have that button assign an alias to a column in a saved query, then have the report pull that.
For scope of things, I could have coded a python app to do this in no time, but I don't know enough VBA to get it done, don't need hand holding, but resources, or starting and key points would be helpful.
We are using HP ALM 12.53.193 for issue tracking.
For a progress report of our development activity, I am trying to find out what tickets I worked on within the past month. Primarily, this includes tickets for which my user name was added to the Editors field, or that were marked as Fixed or Closed by me in the given timespan.
I am seeing some promising hints in this forum post that uses SQL to query the AUDIT_LOG table. Likewise, this [sqa.se] post suggests an SQL script for an Excel report.
Unfortunately, when I click New Business View Excel Report in ALM, I am asked to upload an Excel file for some reason, so I am not sure how to proceed from there to entering my SQL.
I have also tried creating a report with the New Project Report command (i.e. I am also ok with a non-scripted solution, if that is the way to go in ALM). However, it seems I can only show the filtered contents of single tables (e.g. Defect) there (the "Cross Filter" feature does not let me choose another entity (e.g. the Audit Log) for cross-filtering my defects with).
How can I retrieve that data from ALM?
I am not entirely sure SO is the right site for this question, although I consider HP ALM a "software tool(...) commonly used by programmers". Please migrate if it is deemed a better fit for another site.
I have built a task-tracking database for my department. Tasks are assigned to staff in the "Assignee" field of the tasks table, which is actually a reference to the Staff table.
Once a week, I need to send out a report to each person, each report personalized to filter only those tasks they are assigned to. Simple enough for me to create manually, but creating one for each person is time-consuming and tedious. I have found code for outputting and/or emailing a report, but neither allows me to filter the reports via VBA. Ideally, I would simply create a loop that would fire these reports off one by one, applying the filter and sending the email to the corresponding staffer (the Staff table also contains their emails). I'm open to an intermediate step where the report is first saved somewhere if this makes it easier.
I cannot find a way to filter a report via VBA as I am exporting or emailing it. I have contemplated just creating the pre-filtered reports in advance and simply emailing these out, but this is not a dynamic method as it will not automatically account for staff changes, and I do not expect my successor to be VBA-friendly.
Help is much appreciated.
I am building an Access 2010 db which will store and query information relating to time spend by users in our team. Part of the reporting needs to include whether timesheets have been submitted on time.
The process is currently being managed in Excel but is becoming cumbersome due to the growing size of the consolidated data. In the current process, the flag on whether someone is late with their timesheet is applied manually.
Instead of manually adding a Yes / No value to the excel data, I wondered whether it was possible to set up separate TransferSpreadsheet processes in Access to upload the excel data (and attach them to separate command buttons) such that, depending on which one is executed, the import process adds a Yes or a No value to the last column in the data as it's being uploaded.
That way we can import the excel data for those who submitted their timesheets on time (and 'stamp' them Yes for being on time) and then any subsequently late submitted timesheet data can be imported later (and 'stamped' with a No).
I have spent several hours looking at online forums and instruction pages but cannot find anything close to what I am trying to achieve, hence the reason for posting this here.
This is just one of the options I am considering but my VBA skills are insufficient to establish whether such a process could be handled in VBA. All help appreciated. Thanks.
Solved this one myself with a bit of perseverance. Ended up running a few DoCmd.RunSQL commands to Alter / Delete / Insert the tables I had and used a 'join' table to load the data from excel and then ran a command to append the data from the 'join' table to the main table. I just invoke slightly different commands to update the table field based on whether the data has been submitted late or on time.