code: public FKeyModel fkey(String fkeyName) {
  		checkReadOnly();
  		FKeyModel fkey = new FKeyModel();
  		fkey.setTableName(this.tableName);
  		fkey.setFkeyName(fkeyName);
  		fkey.setTableModel(this);
  		getFkeyConstraints().add(fkey);
  		return fkey;
  	}
docs: Start add a foreign key definition in DDL, detail usage see demo