code: protected Field getField(int columnIndex) throws SQLException {
      if (columnIndex < 1 || columnIndex > fields.length) {
        throw new PSQLException(
            GT.tr("The column index is out of range: {0}, number of columns: {1}.",
                columnIndex, fields.length),
            PSQLState.INVALID_PARAMETER_VALUE);
      }
      return fields[columnIndex - 1];
    }
docs: For several routines in this package, we need to convert a columnIndex into a Field[]
  descriptor. Rather than do the same code several times, here it is.
  
  @param columnIndex the first column is 1, the second is 2...
  @return the Field description
  @exception SQLException if a database access error occurs