I'm am fairly new to android and I made an app that creates, modifies and deletes users using SQLite. What I want to do is that after, lets say a week after a user is created, it deletes itself without the administrator having to do it himself.
Is there a way to do this? Thank you for your answers
You'll have to store a creationDate with the user then make a service that runs sql command, let's say each night, to see wich users are more than a week old.
I don't think there is a way that the database detects it alone.
Here is a link about AlarmManager it's usefull to run background stuff at set times.
So I created two rows in my SQLite DB and made a timestamp with the current date.
The second row was a TEXT and I made the user pick the expiration date using a CalendarView.
To delete the row I used the delete method. Since this method return an int value, I made it launch a Toast to say how many rows where deleted
Related
I'm using java and I have a software that registers a patient and save it in a database, but there are some attributes that must be changed every time and I dont know how to do it:
My table(patients):
1.Name: (patient's name) [varchar].
2.CPF:(is a personal number that Brazilians uses to identify yourself, everybody has one), [varchar].
3.Notes:(patient's progress after the scessions) the patient will receive a bunch of notes, so it should be an array.
After one note saved, I would like to save more after...
As after the update, you Need to update the notes for the patient. So what you can do is create a table called Patient_Notes where it will have the reference from the patient table (patient_id). By this, you can store all the notes for the patient. And also you won't need to update the same. You can just fetch the last one and also you will the have the records for all the notes that have been made.
I have enabled the Firebase Persistance in my application. If I am setting a value to a child such as
child.setValue("XYZ");
I am not adding value to the parent tree. I am just updating the value of one child. So here, the value will be updated again and again by the user as he uses the application like many times a day. So, my question is, if user do not have inter-net connection for days, will this thing generate bug as Firebase is storing these things in cache. Does all the data get stored offline with mechanism something like commits in git or just the latest value is stored. I am asking this thing because it's kind of cache so if firebase stores data with all the logs and values the child gets then it can make my application buggy and slow as it will carry all the cache all the time.
If you are getting offline and you are updating a single record than, when your getting back online, only your last update will be updated on the server. Let's take an example. You have a product in which you store a timestamp. Every time you make an update, you change that timestamp with the current timestamp. If you are offline and you edit that product several times, when you'll be back online, only the last timpstamp will be added on the server.
But remember, this not happening when you add new data. When you do this, all the new data is added on the server accordingly to time you have added. This happening also when you delete.
Hope it helps.
Let's say you have a database table name table1 with columns name and surname. Two different clients open the same view from the java application and get the data for same person at the same time.
1) First client changed the name and pressed save button to update database record.
2) Client2 still sees the old record on the screen and then pressed to save button to change the surname.
It actually overwrite the record by old name. I think to check and get the latest data before updating the database when I click button but I do not like this solution because of making a second query before update.
So how can we solve this problem by using Hibernate and without using Hibarnete. Any idea?
Of course if you do not want that something will be overridden, then you have to check the data before an update. But it will be not always a real query with a good caching strategy. You could also use a timestamp with last update to compare it easier. Another strategy would be to lock the entities when the first user will read them. But that is normally not a good design for web applications or you have to integrate a messaging service, which will all user inform for an update who actually have open that entity. But I think that is not so easy to implement and a more advanced feature.
In short, compare the timestamp of an entity and if already updated, then compare the changes and show them for the user who wanted update that entity.
Am working on one of my requirement, halfway through am stuck on an issue. As per my requirement I need to know if any calendar event has been updated, say like any new participant is added or any event fields has been updated say Title,Description or location. As of now am able to know precisely if any event is added or deleted from system, but unfortunately am not able to detect out any update.
The same scenario goes to media, i need to know if any fields related to a media is changed, say name,title or parent folder/path etc.
to summaries my requirement is to know if any filed in Media or Calendar db is updated. to detect Insert or Delete am using Content Observers, as it only tells me something is changed by through onChange() call back, but it never tells you which rows was updated.
regards,
techfist
I had a similar problem with the browser. I made use of shared preferences.
When I read the DB, I know that I have read all the entries until the time stored in shared preferences. So each time I read DB, I need to check for all the changes after the time that was stored in shared preferences and update the time in the shared preferences to current time. For code and my implementation can can look to my solution in Android History Content Observer
I have an employee and a corresponding employee history table.
Both the tables have same structure. History table is used to track the historical changes made to the employee over a period of time.
Now, I need to add an undo function to the changes made to the employee.
e.g. Employees title is changed on 1st August. Now, This will update the employees title in Employee table and insert an corresponding history record in employee_history table.
Now, I need to undo this change. Employee edit page will have a list of changes made to employee datewise with an undo button beside it.
Clicking on undo should revert changes in Employee table to previous value. Also I think the record in history table which says title is changed, should also be removed.
Also when I revert tghe changes to employee table i.e. revert title to previous title, this will fire an insert to history table, which I dont want.
I am not sure what is the best possible way to do this.
Any suggestions will be helpful.
In case you want to implement a "persistent" undo - one that would survive an application restart/session timeout, you should consider extending your DB schema width timestamp fields and either delete the last entry or replace it with an appropriate earlier entry.
A "light" version would be using a stack to store last interactions, including the original and the new value. You could persist the stack on session invalidation of course to combine both approaches. This seems to be what you are actually doing.
You could extend this solution by creating and storing or exporting SQL migration scripts for each change, recording the change and, if possible, the opposite action. So you could even transfer the scripts between application instances and environments and would have a complete "replayability" of your DB states.
tl;dr - it looks like you have already implemented a good solution
I would suggest using a flag telling the trigger/history logic to keep off while you have your undo running and not writing history data.
Normally this would be done by serializer-class feeding from your history table and restoring employee data and later cleaning up history-entries/unlocking history again.
You could maybe use the rollback feature of the transaction.