code: public T updateColumn(final Connection _con,
                            final String _tableName,
                            final String _columnName,
                            final ColumnType _columnType,
                            final int _length,
                            final int _scale)
          throws SQLException
      {
          final StringBuilder cmd = new StringBuilder();
          cmd.append("alter table ").append(getTableQuote()).append(_tableName).append(getTableQuote())
              .append(getAlterColumn(_columnName, _columnType));
          if (_length > 0) {
              cmd.append("(").append(_length);
              if (_scale > 0) {
                  cmd.append(",").append(_scale);
              }
              cmd.append(")");
          }
          AbstractDatabase.LOG.debug("    ..SQL> " + cmd.toString());
  
          final Statement stmt = _con.createStatement();
          try {
              stmt.execute(cmd.toString());
          } finally {
              stmt.close();
          }
          @SuppressWarnings("unchecked")
          final T ret = (T) this;
          return ret;
      }
docs: Adds a column to a SQL table.
  
  @param _con SQL connection
  @param _tableName name of table to update
  @param _columnName column to update
  @param _columnType type of column to update
  @param _length length of column to update (or 0 if not specified)
  @param _scale scale of the column (or 0 if not specified)
  @return this instance
  @throws SQLException if the column could not be added to the tables