The model consists of four layers - DDL, DML, DPL and CL.該模型分為數(shù)據(jù)定義層DDL、 數(shù)據(jù)操縱層DML 、 數(shù)據(jù)顯示層DPL和控制層CL四層, 這里重點闡述了DDL和DML層.Availability of database definition language ( DDL ) and database manipulation language ( DML ) in DAO ...