Android: add column to Database [duplicate]

This question already has an answer here:

• When is SQLiteOpenHelper onCreate() / onUpgrade() run? 3 answers

I'm trying to update my database and I need to add a column to a table, TABLE_GASTO, the problem is that when I execute the app the column is not being add and I get the error

"java.lang.IllegalArgumentException: column 'MOEDA' does not exist" when I executegasto.setMoedaMes(cursor.getString(cursor.getColumnIndexOrThrow(col_MOEDA))); after a SELECT.

DataBase:

private static final String UPD_GASTOS_EURO = "UPDATE " + TABLE_GASTOS + " (" + col_MOEDA + ")" + " VALUES('Euro');";
private static final String COUNT_GASTOS = "SELECT COUNT(*) FROM "+ TABLE_GASTOS + " WHERE " +col_MOEDA+" IS NULL;";

public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

        db.execSQL("DROP TABLE IF EXISTS " + TABLE_CURRENCY);
        db.execSQL("ALTER TABLE "+TABLE_GASTOS+" ADD COLUMN "+col_MOEDA+";");
        db.execSQL("INSERT INTO " + TABLE_CURRENCY + " (" + col_MOEDA + ") VALUES (" + Euro + ");");

        Cursor cursor = db.rawQuery(COUNT_GASTOS, null);

        if(cursor != null){
            cursor.moveToFirst();
            if(cursor.getCount()>0)
                db.execSQL(UPD_GASTOS_EURO);
        }
    }

Chamada :

  public List<Gasto> getAllGastos(){

   List<Gasto> gastos = new ArrayList<>();
        SQLiteDatabase db = this.getWritableDatabase();

    String selectQuery = "SELECT * FROM " + TABLE_GASTOS;
    Cursor cursor = db.rawQuery(selectQuery, null);

    if (cursor !=null) {
        while (cursor.moveToNext()) {

            Gasto gasto = new Gasto();

            gasto.setMes(cursor.getString(cursor.getColumnIndex(col_MES)));
            gasto.setAno(cursor.getInt(cursor.getColumnIndex(col_ANO)));
            gasto.setMeta(cursor.getInt(cursor.getColumnIndex(col_META)));
            gasto.setDespesa_final(cursor.getDouble(cursor.getColumnIndex(col_DESPESA_FINAL)));
            gasto.setDespesa(cursor.getDouble(cursor.getColumnIndex(col_DESPESA)));
            gasto.setMoedaMes(cursor.getString(cursor.getColumnIndexOrThrow(col_MOEDA)));
            gasto.setData_cria(new Date(cursor.getLong(4)));
            gasto.setData_modif(new Date(cursor.getLong(4)));
            gastos.add(gasto);
        }
    }
    db.close();
    return gastos;
}

Can you help me?