sqlite database android get all column values into string array

Question

I have a sqlite database in android , for example :

Table 1 person:

• column 1: id
• column 2: name
• column 3: friends

Table 2 friends:

• column 1: id
• column 2: allFriends

the id is the same in both tables, id in table1 == id in table2 i want to get all the values from table2 in specific column "allFriends" by the id and insert all the String values from the column into String array / arrayList.

Answer 1

Try this,

  public ArrayList<String> getAllFriends(int id) {
    ArrayList<String> friendsNames = new ArrayList<>();
    SQLiteDatabase sqLiteDatabase = null;
    try {
        String query = "select * from person P join friends F on F.id = P.id where P.id = " + id;
        Cursor cursor = sqLiteDatabase.rawQuery(query, null);
        while (cursor.moveToNext()) {
            friendsNames.add(cursor.getString(cursor.getColumnIndex("allFriends")));
        }
    }catch(Exception ex){
        Log.e(TAG,"Erro in geting friends "+ex.toString());
    }
    return friendsNames;
  }

Answer 2

Your SQL query:

SELECT allFriends FROM friends where id == Id_from_person

Id_from_person - id of person who friends you want to recieve from DB.
For executing query read this .