Question

I wanted to know something which is very disturbing for me. i.e.

Lets say I have an App. which is in the Appstore and running fine.
This App. has a local database with lets say 5 tables.

I update this App. and add 2 more new tables, which makes it a total of 7.

When the previous app version users will upgrade to the newer version. Will the database be updated also for the previous version users ?

If yes ?
then will the previous data will be removed.

If not
then the code will obviously make some crashes as it is going to need the new things which are not replaced.

Waiting for your precious comments.

Answer 1

If the database is based on coredata then you will need to use .

But if you are using sqlite DB

Then you can save the version number of your app into your db and whenever database is called(with new installation/upgrade), compare the version against the expected version If new version > older version then change the schema (this is needed if you would have changed the schema of your database) with using SQL ALTER statements and update the app version number. so whenever user is going to update or fresh installation, it will check the new version with your older version,

if it differ then 
    update schema, 
and if its same 
    no need to make any changes.

If you would not have made any schema related changes (for example adding new column..) then you do not need to worry, user will not lose the data.