Concrete Table Inheritance - Represents an inheritance hierarchy of classes with one table per concrete class in the hierarchy. Concrete Table Inheritance对继承体系结构中的每一个具体类都有一个表与其对应。需要保证同一个类体系结构中表的主键不重复。DBMS不能帮助你,你需要自己进行控制。很多情况下你都不能...
Inheritance. Figure 9.18 shows the inheritance relationship between the Bike and SpecialistBike classes in the Wheels system. Sign in to download full-size image Figure 9.18. Inheritance relationship between the Bike and SpecialistBike classes There are three different ways of implementing an inheritance...
Supports table inheritance SQLite: Uses dynamic typing Supports auto-incrementing primary keys with INTEGER PRIMARY KEY or AUTOINCREMENT Oracle: Requires double quotes for case-sensitive identifiers Offers complex data types Uses sequences to create automatically incrementing primary keys SQL Server: Uses...
Modeling Composition in a Java Class Diagram Modeling Inheritance on a Java Class Diagram Extending Modeled Java Classes Implementing Modeled Java Interfaces Modeling Java Fields and Methods Refactoring Class Diagrams Modeling with EJB Diagrams Working with EJB/JPA Modeling Features Create a Di...
This assumed behavior of joins is referred to as "inheritance of filter selectivities by detail tables." Thus, a filter on headers selecting 1% of the headers should result in a join to about 1% of the lines, and 3% of the customers should join to about 3% of the orders. Occasionally,...
The benefits of an object-oriented approach arise out of three basic principles: encapsulation, polymorphism and inheritance. Generally speaking, from a programming point of view, an object model is a unifying set of rules that describe object structure, object lifecycle, and inter-object communicatio...