String getSQLWhere() {
    switch (relationship) {
      case NOT_EQUALS:              return columnName + " <> ?";
      case GREATER_THAN:            return columnName + " > ?";
      case GREATER_THAN_OR_EQUALS:  return columnName + " >= ?";
      case LESS_THAN:               return columnName + " < ?";
      case LESS_THAN_OR_EQUALS:     return columnName + " <= ?";
      case LIKE:                    return columnName + " LIKE ?";
      default:                      return columnName + " = ?";
    }
  }