在升级应用程序时删除SQLite数据库

Question

I implemented an Android application which use Sqlite database.

When I release a new version of my application (not in playStore), I upload it on my server, so, if the old application is running, calling web service, can understand that new version is available. So, new version is downloaded and installed.

When the application is overinstalled, the database is not dropped, so if I need to do any changes of my database I need to use the method:

public void onUpgrade(SQLiteDatabase _db, int oldVersion, int newVersion)

This is fine, unless I need to do many changes in my database. In this case, the code becomes unreadable. So I would to delete the database and create a new one.

How can I perform this task?

EDIT : What about using context.deleteDatabase(DATABASE_NAME); ?

Answer 1

For throw-away databases (where the data is eg a cached copy of data available in the cloud) I usually make onUpgrade() just call onCreate() and make onCreate() execute DROP TABLE IF EXISTS <tablename> before creating the tables.

For example:

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
  onCreate(db);
}

@Override
public void onCreate(SQLiteDatabase db) {
  db.execSQL("DROP TABLE IF EXISTS foo");
  db.execSQL("CREATE TABLE foo(bar INTEGER, baz TEXT");
}

Answer 2

you can think about this one

keep a trace of your upgrade using a flag in shared preference. when you are downloading new version then set the flag to true. on every launch check the flag. if the flag is true then recreate the database and set the flag false.

I havn't tried similar things but I think it should work in your case.

and to delete database context.deleteDatabase(DATABASE_NAME);

Answer 3

如果您只想重新创建整个数据库，只需将每个表都放在旧表中即可。