I have a db containing info for a party.
I have a look-up field for who invited them, this is just a list of 4 names.
When I change this it changes characters in the last name column of the same row to ones that weren't even in the normal Latin alphabet.
The reverse happened as when I went to change it back it then changed the invited by column into some Chinese (looking) characters, breaking it's own validation as I said only items in the list were allowed, but it was fine with that for some reason.
Any idea what could be going on in this situation?
Also when I create a new table it doesn't appear in the Access Objects list until I reopen the database
The issue seems to have been caused by some corruption in the Access database file. Performing a "Compact and Repair Database" operation in Access appears to have resolved it.
Related
We have data stored in encrypted fields (with SQL Server encryption) in our database and we have a requirement to be able to remove certain records from our database under certain peculiar conditions that I will spare you. However it has been noted by a DBA that simply nulling out the data potentially still leaves residual data in the file so it could potentially be recovered.
It has been suggested by someone in the team that (rather than nulling) we write a '*' for each character we want to remove then delete the record, and they assert that this will wipe the data so if someone gets hold of the mdf file the value won't be retrievable (because the bits have been overwritten). For example if we have a value "abc" we run an update statement that replaces this value with '***'. Then we delete the record.
Can anyone confirm if this is the case? Personally I'm skeptical, but I'm a developer and not a DBA so this isn't an area of specialty for me.
BACK END - SQL Server
FRONT END - Access 2010 (2000 format)
The system stores and retrieves data about technical documents. Broadly, there are three tables A, B and C, each of which maintains data about a different type of document.
The ACCESS front end provides a Search Form and Data Entry/Edit form (bound to the underlying table) for each document type. In all three document types, when adding a new record, the user will open the Search form and press a button called "Add". This opens the Data Entry/Edit form and in the Form_Load event is the line
DoCmd.GoToRecord , , acNewRec
When the data entry is complete, the user presses a "Close" button which simply runs the code
DoCmd.Close
As I said, the design and code of the objects relating to the three document types is, for all intents and purposes, identical. However, while for tables A and B the process of adding a new record is seamless and extremely quick, for table C it has proved impossible to add a new record via the ACCESS UI. The edit form will open correctly to add the data, but when the user presses the "Close" button the form hangs, and eventually returns to the Search form without the new record having been added.
It is possible to bypass the UI by opening ACCESS while holding down the SHIFT key, opening the linked table, and adding new records directly. While this is acceptable as an interim measure, it is unacceptable in the long term. It should be noted that the system is about ten years old, and has been working entirely correctly for about nine of those years (apart from minor glitches moving between different versions of ACCESS).
Unfortunately this system is owned and operated by a major global corporation and it is very difficult for me, a subcontracted supplier, to get access to the SQL Server box to run diagnosis (SQL Profiler would be a good starting point). My gut feeling is that there is a subtle difference in the permissions model for that particular table but I don't know.
The situation is further complicated by the fact that I have a copy of the system at my work and I cannot reproduce the problem. Of course, there are bound to be subtle differences between the two architectures (for example, I don't know for certain what version of SQL Server it's running on, but I believe it's 2000, nor do I know how completely it is patched or updated) but the facts are that for one particular table bound to one particular form, it is not possible to add records, whereas for other tables there is no such problem.
I would be grateful if anyone has any ideas about how to go about diagnosing this or even solving it (if anyone has come across the same problem before).
Many thanks
Edward
As a general rule when you encounter problems to update a table, then this tends to suggests that the table does not have a PK or the form the query is based on does not have a PK exposed.
The next thing I would ensure is the table has a time stamp column as Access uses this to test for record changes behind the scenes.
Next up I would check the default locking for the form (while these settings generally don't effect odbc, they should be checked).
Next up is to check if the table has any "bit" column (true/false) and ensure that the defaults for such controls are set SQL SERVER side (they should default to 0). This null bits issue will cause updates to fail if not addressed.
I would also check if the form in question is based on a query or if the data source is set directly to the table. As noted the PK auto number ID of that table in query should be INTEGER value sql side – big int is NOT supported.
So check default values (both in sql table and on the form (those controls) to ensure nothing be set that would prevent the update.
I have a huge database (800MB) which consists of a field called 'Date Last Modified' at the moment this field is entered as a text data type but need to change it to a Date/Time field to carry out some queries.
I have another exact same database but with only 35MB of data inside it and when I change the data type it works fine, but when I try to change data type on big database it gives me an error:
Micorosoft Office Access can't change the data type.
There isn't enough disk space or memory
After doing some research some sites mentioned of changing the registry file (MaxLocksPerFile) tried that as well, but no luck :-(
Can anyone help please?
As John W. Vinson says here, the problem you're running into is that Access wants to hold a copy of the table while it makes the changes, and that causes it to exceed the maximum allowable size of an Access file. Compacting and repairing might help get the file under the size limit, but it didn't work for me.
If, like me, you have a lot of complex relationships and reports on the old table that you don't want to have to redo, try this variation on #user292452's solution instead:
Copy the table (i.e. 'YourTable') then paste Structure Only back
into your database with a different name (i.e. 'YourTable_new').
Copy YourTable again, and paste-append the data to YourTable_new.
(To paste-append, first paste, and select Append Data to Existing
Table.)
You may want to make a copy of your Access database at this point,
just in case something goes wrong with the next part.
Delete all data in YourTable using a delete query---select all
fields, using the asterisk, and then run with default settings.
Now you can change the fields in YourTable as needed and save
again.
Paste-append the data from YourTable_new to YourTable, and check
that there were no errors from type conversion, length, etc.
Delete YourTable_new.
One relatively tedious (but straightforward) solution would be to break the big database up into smaller databases, do the conversion on the smaller databases, and then recombine them.
This has an added benefit that if, by some chance, the text is an invalid date in one chunk, it will be easier to find (because of the smaller chunk sizes).
Assuming you have some kind of integer key on the table that ranges from 1 to (say) 10000000, you can just do queries like
SELECT *
INTO newTable1
FROM yourtable
WHERE yourkey >= 0 AND yourkey < 1000000
SELECT *
INTO newTable2
FROM yourtable
WHERE yourkey >= 1000000 AND yourkey < 2000000
etc.
Make sure to enter and run these queries seperately, since it seems that Access will give you a syntax error if you try to run more than one at a time.
If your keys are something else, you can do the same kind of thing, but you'll have to be a bit more tricky about your WHERE clauses.
Of course, a final thing to consider, if you can swing it, is to migrate to a different database that has a little more power. I'm guessing you have reasons that this isn't easy, but with the amount of data you're talking about, you'll probably be running into other problems as well as you continue to use Access.
EDIT
Since you are still having some troubles, here is some more detail in the hopes that you'll see something that I didn't describe well enough before:
Here, you can see that I've created a table "OutputIDrive" similar to what you're describing. I have an ID tag, though I only have three entries.
Here, I've created a query, gone into SQL mode, and entered the appropriate SQL statement. In my case, because my query only grabs value >= 0 and < 2, we'll just get one row...the one with ID = 1.
When I click the run button, I get a popup that tells/warns me what's going to happen...it's going to put a row into a new table. That's good...that's what we're looking for. I click "OK".
Now our new table has been created, and when I click on it, we can see that our one line of data with ID = 1 has been copied over to this new table.
Now you should be able to just modify the table name and the number values in your SQL query, and run it again.
Hopefully this will help you with whatever tripped you up.
EDIT 2:
Aha! This is the trick. You have to enter and run the SQL statements one at a time in Access. If you try to put multiple statements in and run them, you'll get that error. So run the first one, then erase it and run the second one, etc. and you should be fine. I think that will do it! I've edited the above to make it clearer.
Adapted from Karl Donaubauer's answer on an MSDN post:
Switch to immediate window (Ctl + G)
Execute the following statement:
DBEngine.SetOption dbMaxLocksPerFile, 200000
Microsoft has a KnowledgeBase article that addresses this problem directly and describes the cause:
The page locks required for the transaction exceed the MaxLocksPerFile value, which defaults to 9500 locks. The MaxLocksPerFile setting is stored in the Windows registry.
The KnowledgeBase article says it applies to Access 2002 and 2003, but it worked for me when changing a field in an .mdb from Access 2013.
It's entirely possible that in a database of that size, you've got text data that won't convert to a valid Date/Time.
I would suggest (and you may hate me for this) that you export all those prospective date values from "Big" and go through them (perhaps in Excel) to see which ones are not formatted the way you'd expect.
Assuming that the error message is accurate, you're running up against a disk or memory limitation. Assuming that you have more than a couple of gigabytes free on your disk drive, my best guess is that rebuilding the table would put the database (including work space) over the 2 gigabyte per file limit in Access.
If that's the case you'll need to:
Unload the data into some convenient format and load it back in to an empty database with an already existing table definition.
Move a subset of the data into a smaller table, change the data type in the smaller table, compact and repair the database, and repeat until all the data is converted.
If the error message is NOT correct (which is possible), the most likely cause is a bad or out-of-range date in your text-date column.
Copy the table (i.e. 'YourTable') then paste just its structure back into your database with a different name (i.e. 'YourTable_new').
Change the fields in the new table to what you want and save it.
Create an append query and copy all the data from your old table into the new one.
Hopefully Access will automatically convert the old text field directly to the correct value for the new Date/Time field. If not, you might have to clear out the old table and re-append all the data and use a string to date function to convert that one field when you do the append.
Also, if there is an autonumber field in the old table this might not work because there is no way to ensure that the old autonumber values will line up with the new autonumber values that get assigned.
You've been offered a bunch of different ways to get around the disk space error message.
Have you tried adding a new field to your existing table using Date data type and then updating the field with the value the existing string date field? If that works, you can then delete the old field and rename the new one to the old name. That would probably take up less temp space than doing a direct conversion from string to date on a single field.
If it still doesn't work, you may be able to do it with a sceond table with two columns, the first long integer (make it the primary key), the second, date. Then append the PK and string date field to this empty table. Then add a new date field to the existing table, and using a join, update the new field with the values from the two-column table.
This may run into the same problem. It depends on number of things internal to the Jet/ACE database engine over which we have no real control.
I have a database that I just converted the back end to SQL Server using SSMA. I left the front end in MS Access. I only converted the tables and not the queries. It already had some data in it and that moved over just fine.
All was going well until just recently. On opening the database and loading the main form Event Interest it started having problems with the first record of the subform, called Names. The first field in the first record has data sometimes and not others. This is a text field. When data is in the field it puts in random numbers. I believe they may be related to SQL somehow. When there is no data/missing you can select the field and hit the backspace button and the data will appear minus the one character you just errased. I have no idea what is going on.
Any help you can supply I would greatly appreciate it. Thank you in advance.
I am new to SQL Server and I have used older versions of MS Access for a few years.
I am not certain what the problem might be, but these are some considerations that come to mind:
try deleting and recreating your linked tables. Perhaps an update to the table structure (or view, if you're linked to a view) has invalidated some of the metadata stored in the table link in your front end.
does your table have a primary key? If not, you really need one. There really is no such thing as a properly-designed data table in a relational database that is PK-less.
does your table have a timestamp? If not, add one, as this helps Access keep track of whether or not the data has changed on the server.
However, let me add that none of these issues manifest themselves exactly with the symptoms you've described, so they may not help.
I'm at a client doing some quick fixes to their access application. It was a while I had a go with access, but I'm recovering quickly. However, I've discovered an interesting problem:
For some reports, I get a "Record is deleted" error. I've checked the reports, and it seems like there's a problem with one table. When opening that table, I find a record where all columns are marked "#deleted". So obviously, this row seems to be the culprit. However, when I try to delete that row, nothing really happens. If I re-open the table, the row still exists.
Is there a corruption in the db? How can I remove this record for good?
Edit: It's a MS2000-version
Solution: Simply compress/repair did not work. I converted the database to the 2003 file format instead, which did the trick. I've marked the first answer suggesting compress/repair, since it pointed me in the right direction. Thanks!
Have you tried the built in Access compact/repair tool? This should flush deleted records from the database.
The exact location varies according to the version of Access you're running, but on Access 2003 it's under Tools > Database Utilities > Compact and repair database. Some earlier versions of Access had two separate tools - one for compact, one for repair - but they were accessed from a similar location. If they are separate on the version the client has, you need to run both.
This should be a non-destructive operation, but it would be best to test this on a copy of the MDB file (apologies for stating the obvious).
Tony Toews, Access MVP, has a comprehensive guide to corruption:
Corrupt Microsoft Access MDBs FAQ
Some corruption symptoms
Determining the workstation which caused the corruption
Corruption causes
To retrieve your data
As an aside, decompile is very useful for sorting out odd happenings when coding and for improving start-up times.
you can also try this Command line utility
//andy
Compacting and importing won't fix the problem for the error reported, which is clearly a corrupted pointer for a memo field. The only thing you can do is delete and recreate the record that is causing the problem. And you need to find ways to edit memo data (or eliminate memo fields -- do you really need more than 255 characters or not?) that does not expose you to corruption risk. That means avoiding bound controls on forms for memo fields.
Instead, use an unbound textbox, and in the form's OnCurrent event, assign the current data from the form's underlying recordsource:
Me!txtMyMemo = Me!MyMemo
To save edits to the unbound control, use the control's AfterUpdate event:
Me!MyMemo = Me!txtMyMemo
Me.Dirty = False ' save the whole record
Why are memo fields subject to corruption? Because they aren't stored in the same data page as the non-memo fields, but instead, all that is in the record's main data page is a pointer to some other data page (or set of data pages if it's a large chunk of data) where the actual memo data is stored. If it weren't done this way, a record with a memo in it would very quickly exceed the maximum record length.
The pointer is relatively easily corrupted, most often by a fatal problem during editing in a bound control. Editing with an unbound control does not eliminate the problem entirely, but means that the time in which you're exposed to danger is very, very short (i.e., the time it takes for those two lines of code to execute in the AfterUpdate event).
Aside from the options already posted above, I've used another simple method aswell: Simply create a new MDB file and import all objects from the corrupted one. Don't forget to get system and/or hidden objects when you go this way.