表已更新，但未返回正确的值

Question

Probably something simple but it's taking me a long time to figure out.

I want to save a rating bar rating and then load that rating when i re-open the actvity. But it is always returning 0.

I have a recipe table with a rating column:

final String CREATE_TABLE_RECIPES = "CREATE TABLE IF NOT EXISTS " +
        TABLE_RECIPES + "(" +
        RECIPE_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
        RECIPE_NAME + " TEXT, " +
        RECIPE_INSTRUCTIONS + " TEXT, " +
        RECIPE_RATING + " FLOAT " +
        ")";

I have an onRatingBarChange Listener to save the rating to table:

(The values for id and rating are correct)

ratingbar.setOnRatingBarChangeListener(new RatingBar.OnRatingBarChangeListener() {
        @Override
        public void onRatingChanged(RatingBar ratingBar, float rating, boolean fromUser) {
            db.addRating(id, rating);
       }
});

The addRating method in db class:

public void addRating(int id, float rating) {
    String SET_RATING =
            "UPDATE " + TABLE_RECIPES +
                    " SET " + RECIPE_RATING + " = " + rating +
                    " WHERE " + RECIPE_ID + " = " + id;

    SQLiteDatabase db = this.getWritableDatabase();
    db.rawQuery(SET_RATING, null);
    db.close();
}

and finally, the getRating method in db class:

public float getRating(int id) {
    String GET_RATING =
            "SELECT " + RECIPE_RATING +
                    " FROM " + TABLE_RECIPES +
                    " WHERE " + RECIPE_ID + " = "  + id;
    SQLiteDatabase db = this.getReadableDatabase();
    Cursor c = db.rawQuery(GET_RATING, null);
    c.moveToFirst();
    float rating =  c.getFloat(0);
    Log.i("getRating", "gotRating: " + rating);
    return rating;
}

The returned rating is always 0, so either it is not saving properly or it is not getting the value properly.

Answer 1

 db.rawQuery(SET_RATING, null); 

You should use execSQL() for UPDATE queries, not rawQuery() . (Or one of the convenience wrappers such as update() .)

rawQuery() compiles the underlying SQL but does not execute it; execSQL() both compiles and runs the SQL.