you can use this method to check the value is exist in database or not.
I hope it will be helpful for you:

public boolean isRecordExist(String TableName, String columnName,
                                        String value) {
      DbHelper  dbHelper = new DbHelper(this);
      dbHelper.createDataBase();
      SQLiteDatabase sqldb = dbHelper.openDataBase();
      String Query = "Select * from " + TableName + " where " + columnName + "='" + value + "'";
      Cursor cursor = sqldb.rawQuery(Query, null);
      if (cursor != null && cursor.getCount() <= 0) {
          cursor.close();
          return false;
      } else if (cursor != null) {
          cursor.close();
      }
      return true;
}