Android : Sqlite Update query syntax error

whenever I try to update details I get syntax error near nRating

 public void addRating(String name, String nDate, String nRating,
    String nComment)
{

SQLiteDatabase data = this.getWritableDatabase();

Cursor query = data.rawQuery("update Station Set " + " date " + " = "
    + nDate + "," + " rating " + nRating + "," + " comments "
    + nComment + " Where Stationname " + " = " + name, null);
query.close();

}