I need a trigger to log updates on a table. As I want to log it I need to know the name of the updated column(s) in the trigger body. We have NEW and OLD but it doesn't tell me which column were updated.
If nothing else, I still have the choice between these two ugly solutions:
use one IF NEW.val <> OLD.val per column
use one trigger per column
PS: I saw this "COLUMNS_UPDATED" in SQL which represents what I am looking for.
Related
I am using Cached updates in order to increase speed for my SQLites INSERT queries. The problem I am facing, is that inside the loop where I have my INSERT, I am using an auto-incemental value.
I am using TFDConnection and TFDQuery to implement my database writing part.
Before moving on the next Post() I need the value of the previous auto-incemental value. The problem is that auto-incremental value is not generated unless in call TFDquery.ApplyUpdates().
SO, is there a way that I can use CachedUpdates but also keep Auto-Incremental values that will be generated after calling TFDquery.ApplyUpdates()?
One idea that came up on my mind, is getting the last generated value with TFDConnection.GetLastAutoGenValue() and calculate how many row I will need. For example if I know that I will insert 5 rows and the last auto-generated value was 300, I know that my next values will be 301,302,303,304,305. The whole problem with this, is that I dont have control on which values correlate with the next Post().
What I wanted is to display an alert when I move to the next row if the record that I inserted is already one of the records in the multi record block.
and in what trigger must I put it?
There are several options you can use.
One is to POST values entered (in WHEN-NEW-RECORD-INSTANCE) trigger. It will, well, post everything you entered so far. Then, you can write a WHEN-VALIDATE-ITEM trigger which SELECTs from that table and checks whether such a value already exists. Alternatively, if there's the UNIQUE CONSTRAINT on that (those) column(s), database will do its job itself, i.e. raise an exception.
Another option is to literally loop through all rows in a block and compare the first row's value with all the others, then the second row's values with all of them, etc.
Or, you can use a Record Group (usually used for Lists of Values). Basically, you'd check whether value you entered exists in a record group. More info, along with a FMB file, on Craig's blog.
Or, you can use calculated items, as described enter link description here (FMB attached as well).
As you can see, quite a few ways to do that; explore each of them and pick the one you find the most useful / attractive / easy to implement.
I have a problem that I've been going round and round with in Access 2010. Imagine a table with these columns:
Name Date Time
Now, I have a query that asks the user to input a begin date and an end date and returns all records that are between those two dates. This works fine. However, as soon as I add a sort to the Date column things go awry. Once you put a sort on a column with a parameter the user gets asked to enter the parameter twice. From what I've been able to find out this is normal (although annoying) behavior in Access.
If I add the Date column in a second time and show the column with the sort and don't show the column with the parameter it works fine. The query would look something like:
Name Date (shown & sorted) Date (not shown & parameters) Time
Now when I run the query it all works well and comes out the way I want it to. This would obviously be a great solution then. However, there's another problem. When I save the query, leave, and reopen the query the two columns are merged back into each other. Thus, the change is lost and the user again sees two inputs.
My question is this: what can I do differently to achieve the desired results?
Some possible things I've thought about but don't know the answer to are:
Is there a way to make it so the columns don't merge? Do I have to use a form with the input boxes and take the data from that (I'd prefer not to do that as it will require a lot of additional work to handle the various things I am doing in the database). Is there some obvious thing I'm missing?
Thanks for any suggestions.
FYI: Here is the SQL from the query
SELECT Intentions.Intention, Intentions.MassDate, Intentions.[Time Requested], Intentions.[Place Requested], Intentions.[Offered By], Intentions.Completed
FROM Intentions
WHERE (((Intentions.MassDate) Between [Enter start date] And [Enter end date]))
ORDER BY Intentions.MassDate, Intentions.[Time Requested];
It is true that sometimes the Query Designer in Access will "reorganize" a query when you save it. However, I don't recall an instance where such a reorganization actually broke anything.
For what it's worth, the following query seems to do what you desire. After saving and re-opening it looks and behaves just the same:
For reference, the SQL behind it is
PARAMETERS startDate DateTime, endDate DateTime;
SELECT NameDateTime.Name, NameDateTime.Date, NameDateTime.Time
FROM NameDateTime
WHERE (((NameDateTime.Date) Between [startDate] And [endDate]))
ORDER BY NameDateTime.Date DESC , NameDateTime.Time DESC;
I have had the same problem and I have discovered the reason:
If, after you have run your query, sort a collumn in the result grid and the say yes to save changes to the query the sort action will be stored with the query. This will actually cause the query to run twice. First to create the result and then one more time to sort. You'll therefore be asked twice for the parameters.
SOLUTION: Run the query (entering your parameters twice ;-) ). Then remove the Sorting by clicking on the AZ-eraser symbol in the task bar above (in the sorting compartment).
Then open your query in design-mode and add the sorting order to the appropriate collumn.
Your are then good to go.
Regards
Jan
Im using Asp.net (VB.net), in my Database :
have One table called (Trade), the same rows of this table are used from 3 different users, These users can make different updates on this table, they should see the basic informations of the table (I mean by the Basic, before the table (trade) has been updated)
The problem is here when the first user wants to modify the table's rows, the second and third user cannot see the basic information any more, and if they decide to change or update some data, the first will lose his updated rows..
The data will be overwritten every time the users make updates on the table.
What I want, is to know if there is a way to do like a copy, or an image of the table for the 3 users, and every user can update normally, without creating the same Table with the same rows 3 times??!
Update
My table structure is: Trade(trName, Carrier, POl, POD, Vgp, Qgp) There is no primary key..
Thank you..
Solution to your problem could be two copies of the original table. Show the original table always to the user as the initial data. And in second table keep the updated data always. Now the trick comes here to maintain the log, for that you have to maintain the log table, this table will have all the fields of original table along with one additional column "UserId", this will have the ID of user who has changed the value. Now each time before updating the data, copy it in the log table. If this suits your need then post the fields of your table then we can workout on the table structures.
In a specific table I have a SortOrder integer field that tells my page in which order to display the data. There are sets of data in the this field (based on a CategoryID field), and each set will have its own ordering. Users can add/remove/update records in this table.
My question is what is the best way to manage this SortOrder field? I would like to "reseed" it everytime a record is deleted or updated. Is this something I should be using a trigger for? Or should my code handle it and manage the reseeding?
What I used to do is use only odd numbers in the SortOrder field so upon changing the order, I would add or subtract 3 from the current value of the modified item and then do a reseed (order the items again using odd number indexes). Also I used to reseed after every insert or delete.
All you really have to worry about is swapping any two fields. All new entries go to the end and i'm sure you've got a mechanism by which the user can change the order. The order change, move up or down, really is a swap with a neighboring field. All you really care about is that all the fields are sorted properly. Don't let a mathematical sense of aesthetic drive you into creating something overly complex. (You'll end up with holes in your sequence after deletes are made but that's OK. It's an internal sequence marker used for ORDER BY. the numbers don't need to be made contiguous.)