There are 2 tables: Category (Parent Table) and Product (Sub Table) Create Table [Category] ([ID] [VARCHAR] (10) Not Null, [Name] [VARCHAR] (80) Not Null, [Description] [ VARCHAR] (50) NULL) CREATE TABLE [PRODUCT] ([ID] [VARCHAR] (10) Not null, [CategoryId] [VARCHAR] (10) Not null, [Name] [varchar] (50) Not null, [ Description] [varchar] (50) null) // The following can run ilist data = vsession.Find ("SELECT P.NAME FROM PROMAT AS P LEFT OUTER JOIN P.Categorys As C Where C.ID = '1'") // and write to the following statement but prompt: COULT NOT EXCUTE Query IList Data = vsession.Find ("from product as p left out (" from products as c where c.id = '1'); later finally found an answer : Because both tables have ID this field, all NH0.6.0.0 is unclear,
