Sqliteopenhelper onupgrade when is it called

For this guide, we will imagine we have an app that needs a single SQLite table. This table will be called Team. It will have the following columns: Id int , Name string , City string , Mascot string. When I first started making Android apps, I found a guide that looked something like this Warning: this is not the code you want to copy!

This works great when you are in early development. You can change tables by simply altering the create statement and incrementing the version number and you are good to go! The problem is that this technique will wipe out the table every time it is updated.

That is hardly practical for apps in production. You don't want to be calling:. A developer who realizes this is going to be a problem might Google something like "android onupgrade add column. To view some of these bad solutions just look here , here , here , here , or here! These guides all suggest altering the OnUpdate function to better leverage the oldVersion parameter.

But, they all have a problem. Please enter a valid email id. Password mandatory! Forgot password? Not you? Not using TJ? Create Account. Already a User? Old Fashioned? Sign Up Using Email. Display Name mandatory! Email Please enter a valid email id. Instead, run your query and populate an object with the results. I close the cursor within the function and I'm done. This can also wreak havoc on your app's db connections.

I thought I was doing this but, sure enough, found a spot that I wasn't explicitly closing a cursor. So, go through your app and double check all of them. I'm also using a singleton DatabaseHelper object. I now have a stable running app that no longer gets these DB errors. I hope this information is helpful to some of you. Delete the old database file so that onCreate is run again. This is often preferred at development time where you have control over the installed versions and data loss is not an issue.

Some ways to delete the database file:. Uninstall the application. Use the application manager or adb uninstall your. Increment the database version so that onUpgrade is invoked. This is slightly more complicated as more code is needed. For released versions, you should implement data migration in onUpgrade so your users don't lose their data. So when the database helper constructor is called with a name 2nd param , platform checks if the database exists or not and if the database exists, it gets the version information from the database file header and triggers the right call back.

As already explained in the older answer, if the database with the name doesn't exists, it triggers onCreate.