/// <summary> /// Create foreign key constraint /// </summary> /// <param name="model">Relationship model</param> /// <returns>Exception message if failed, NULL if not</returns> public string AddRelationship(RelationshipModel model) { var ctx = new DatabaseContext(SessionProvider.Instance.ConnectionType); try { ctx.AddRelationship(model); return(null); } catch (Exception exception) when(exception is SqlException || exception is OracleException) { Output.WriteLine(OutputPanelListener.PrepareException(exception.Message)); return(exception.Message); } }