Getting an array of table categorized and cumulated

Question

I have a table that store recent information about Department and bills. My goal is to find the last seven days activities from today date, categorize them by the Department and add up the price and return them as an array.

mysql> select * from Item;
+----+------------+--------------+
| ID | Department | Price | Date
+----+------------+--------------+
|  1 | DELL       | 20    | 04/01/2019
|  2 | HP         | 15    | 04/16/2019
|  3 | DELL       | 30    | 03/15/2019
|  4 | ACER       | 15    | 04/16/2019
|  5 | ASUS       | 60    | 04/15/2019
|  6 | HP         | 15    | 04/14/2019
|  7 | DELL       | 30    | 03/30/2019
|  8 | ACER       | 15    | 01/16/2019
|  9 | ASUS       | 60    | 02/15/2019
+----+------------+----------+

So far I ordered the table by date:

Cursor cursor = db.rawQuery("SELECT * FROM " + Projects_TABLE + " ORDER BY " + PRO_DATE + " DES", null);

and compared the today date minus 7 days stored inside the table, but I don't know how to return every Department accord in the seven days with an added price for example, wanted results of an array:

Today Date is 04/16/2019
+----+------------+----------+
| ID | Department | Price 
+----+------------+----------+
|  1 | HP         | 30 
|  2 | ACER       | 15
+----+------------+----------+

Here is My code

 public  ArrayList<DetailedProject_GS> DB_Display_The_Progress_Weakly() {
        SQLiteDatabase sqLiteDatabase = this.getWritableDatabase ();
        Cursor cursor = db.rawQuery("SELECT * FROM " + Projects_TABLE + " ORDER BY " + PRO_DATE + " DES", null);
        ArrayList<DetailedProject_GS> ProjectsArchive = new ArrayList<>();
        Calendar EndTime = Calendar.getInstance();
        cursor.moveToFirst ();
        while (cursor != null && cursor.getCount () > 0 && !cursor.isAfterLast ()) {
            try {
                SimpleDateFormat simpleDateFormat = new 
 SimpleDateFormat("EEEE dd/MM/yyyy" , Locale.ENGLISH);

                String currentDateandTime = simpleDateFormat.format(new Date());
                Calendar c = Calendar.getInstance();
                c.setTime(simpleDateFormat.parse(currentDateandTime));
                c.add(Calendar.DATE, -7);

                EndTime.setTime(sdf.parse(cursor.getString (cursor.getColumnIndex (PROJECT_H_ENDTIME)) ));// all done
                if (EndTime.after(c)){

                    //Adding CODE HERE
                    ProjectsArchive.add(data);
                }else{

                }
            } catch (ParseException e) {
                e.printStackTrace();
            }
            cursor.moveToNext ();
        }
        cursor.close();
        sqLiteDatabase.close ();
        return ProjectsArchive;
    }

Answer 1

If you change the format of the dates to YYYY-MM-DD, then all you need is group by department:

select 
  department, 
  sum(price) price 
from item
where date >= datetime('now', '-7 day')
group by department

With the current format of the dates, first you must convert it to YYYY-MM-DD:

select 
  department, 
  sum(price) price 
from item
where substr(date, 7) || '-' || substr(date, 1, 2) || '-' || substr(date, 4, 2) >= datetime('now', '-7 day')
group by department