code: public ColumnModel addColumn(String columnName) {
  		checkReadOnly();
  		DialectException.assureNotEmpty(columnName, "columnName can not be empty");
  		for (ColumnModel columnModel : columns)
  			if (columnName.equalsIgnoreCase(columnModel.getColumnName()))
  				throw new DialectException("ColumnModel name '" + columnName + "' already existed");
  		ColumnModel column = new ColumnModel(columnName);
  		addColumn(column);
  		return column;
  	}
docs: Add a column with given columnName to tableModel
  
  @param columnName
  @return the Column object