Use a simple message board example to explain the use of the three-tier structure (factory mode), in which the database operation uses SqlHelper The layered names are: MessagesBoard (web layer), SQLServerDAL, DALFactory, IDAL, BLL Sql database can be attached with a three-layer structure - a simple message board, which is more suitable for beginners. I am also a beginner. Development environment: vs2005+sql2000
