Android upgrade sqlite database issue

问题

I have a little issue with upgrading my sqlite database. For now I'm using this :

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    Log.w("","UPGRADE DATABASE : "+" oldVErsion : "+oldVersion+" newVersion : "+newVersion);
    switch(newVersion){
    case 2:
        Log.w("","UPGRADE DATABASE : "+newVersion);
        db.execSQL("ALTER TABLE collection_lang ADD COLUMN bonus_text VARCHAR(200)");
        db.execSQL("ALTER TABLE collection_lang ADD COLUMN quantity integer");
    case 3:
        Log.w("","UPGRADE DATABASE : "+newVersion);
        db.execSQL("ALTER TABLE users ADD COLUMN firstName varchar(70)");
        db.execSQL("ALTER TABLE users ADD COLUMN lastName varchar(70)");
        db.execSQL("ALTER TABLE users ADD COLUMN user varchar(70)");
    }
}

It's working if you already have the application installed from the beggining..but if you install it now, it will run queries only in case 3, because the current version is 3.

I need to find a way to run the queries from the beginning.. if my last version of database is 5, I want to run first the case 2, than case 3, than 4 and at last case 5. So I won't need to write all the queries from the beginning because it will crash for the old users.

Any ideas how to achieve this?

回答1:

Just add your queries from the case 2 into the case 3 and add break statement after each case. So in your case it will be something like this:

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    Log.w("","UPGRADE DATABASE : "+" oldVErsion : "+oldVersion+" newVersion : "+newVersion);
    switch(newVersion){
    case 2:
        Log.w("","UPGRADE DATABASE : "+newVersion);
        db.execSQL("ALTER TABLE collection_lang ADD COLUMN bonus_text VARCHAR(200)");
        db.execSQL("ALTER TABLE collection_lang ADD COLUMN quantity integer");
        break;
    case 3:
        Log.w("","UPGRADE DATABASE : "+newVersion);
        db.execSQL("ALTER TABLE collection_lang ADD COLUMN bonus_text VARCHAR(200)");
        db.execSQL("ALTER TABLE collection_lang ADD COLUMN quantity integer");
        db.execSQL("ALTER TABLE users ADD COLUMN firstName varchar(70)");
        db.execSQL("ALTER TABLE users ADD COLUMN lastName varchar(70)");
        db.execSQL("ALTER TABLE users ADD COLUMN user varchar(70)");
        break;
    }
}

Update: Do smthg like this:

switch(newVersion){
case 2:
    Log.w("","UPGRADE DATABASE : "+newVersion);
    db.execSQL("ALTER TABLE collection_lang ADD COLUMN bonus_text VARCHAR(200)");
    db.execSQL("ALTER TABLE collection_lang ADD COLUMN quantity integer");
    break;
case 3:
    Log.w("","UPGRADE DATABASE : "+newVersion);
    switch(oldVersion) {
        case 1:
            db.execSQL("ALTER TABLE collection_lang ADD COLUMN bonus_text VARCHAR(200)");
            db.execSQL("ALTER TABLE collection_lang ADD COLUMN quantity integer");
            db.execSQL("ALTER TABLE users ADD COLUMN firstName varchar(70)");
            db.execSQL("ALTER TABLE users ADD COLUMN lastName varchar(70)");
            db.execSQL("ALTER TABLE users ADD COLUMN user varchar(70)");
            break;
        case 2: 
            db.execSQL("ALTER TABLE users ADD COLUMN firstName varchar(70)");
            db.execSQL("ALTER TABLE users ADD COLUMN lastName varchar(70)");
            db.execSQL("ALTER TABLE users ADD COLUMN user varchar(70)");
            break;
    }

}

回答2:

What about to use a loop?

       //or start = oldVersion;              
 for (int start = 2 , start<=newVersion ; start++){
      switch(start){
    case 2:
        Log.w("","UPGRADE DATABASE : "+newVersion);
        db.execSQL("ALTER TABLE collection_lang ADD COLUMN bonus_text VARCHAR(200)");
        db.execSQL("ALTER TABLE collection_lang ADD COLUMN quantity integer");
        break;
    case 3:
        Log.w("","UPGRADE DATABASE : "+newVersion);
        db.execSQL("ALTER TABLE users ADD COLUMN firstName varchar(70)");
        db.execSQL("ALTER TABLE users ADD COLUMN lastName varchar(70)");
        db.execSQL("ALTER TABLE users ADD COLUMN user varchar(70)");
        break;
    default:
        break;
    }

But It is not normal way. As if a user already added some alteration. And you again run that alteration then it will create exception.

回答3:

Instead of nesting a bunch of switches, which will get pretty ugly fast. I would suggest this approach which will cover all scenarios. It will update your existing db (not matter the version) to the current in a step-wise fashion: (as discussed here)

int curVer = oldVersion;
while ( curVer < newVersion ) {
    curVer++;
    switch ( curVer ) {
        case 2: {
            // Upgrade from V1 to V2
            break;
        }
        case 3: {
            // Upgrade from V2 to V3
            break;
        }
        case 4: {
            // Upgrade from V3 to V4
            break;
        }
    }
}

回答4:

Simple,,just have your case conditions in reverse order and dont use break

example in below condition if i value is 3 it will print 3,2,1 if its 4 then 4,3,2,1

switch(i){ case 4: System.out.println("4"); case 3: System.out.println("3"); case 2: System.out.println("2"); case 1: System.out.println("1"); }

来源：https://stackoverflow.com/questions/9109837/android-upgrade-sqlite-database-issue