code: public ColumnModel entityField(String entityFieldName) {
  		DialectException.assureNotEmpty(entityFieldName, "entityFieldName can not be empty");
  		this.entityField = entityFieldName;
  		if (this.tableModel != null) {
  			List<ColumnModel> oldColumns = this.tableModel.getColumns();
  			Iterator<ColumnModel> columnIter = oldColumns.iterator();
  			while (columnIter.hasNext()) {
  				ColumnModel column = columnIter.next();
  				if (entityFieldName.equals(column.getEntityField())
  						&& !this.getColumnName().equals(column.getColumnName()))
  					columnIter.remove();
  			}
  		}
  		return this;
  	}
docs: Mark this column map to a Java entity field, if exist other columns map to
  this field, delete other columns. This method only designed for ORM tool