Chapter 18 - Data Model - Visual Paradigm

SDE-VS User’s Guide (Part 2, for ORM) Chapter 18 –Data Model
18-20
Example:
Figure 18.49 - Copy Statement for create constraint
Create Constraint :
alter table `OrderLine` add index `FK_OrderLine_1969` (`PurchaseOrderPO_NO`), add
constraint `FK_OrderLine_1969` foreign key (`PurchaseOrderPO_NO`) references
`PurchaseOrder` (`PO_NO`);
Drop Constraint :
alter table `OrderLine` drop foreign key `FK_OrderLine_1969`;
Mapping a Data Model to an Object Model
Object Relational Mapping (ORM) is supported which maps data models to object models and vice versa.
Mapping between objects to relational database preserves not only the data, but also the state, foreign/primary key mapping,
difference in data type and business logic. Thus, you are not required to handle those tedious tasks during software
development.
Mapping Entities to Classes
All entities map one-to-one to persistent classes in an object model.
Example:
Figure 18.50 - Mapping entities to classes
In the above example, the Customer Entity map one-to-one the Customer Class as the Customer instance can store the
customer information from the Customer Entity.
Mapping Columns to Attributes
Since all entities map one-to-one to persistent classes in an object model, columns in turn map to attributes in a one-to-one
mapping. All specialty columns such as computed columns and foreign key columns are ignored during the transformation.
Example:
Figure 18.51 - Mapping columns to attributes
In the above example, the following table shows the mapping between the columns of the Customer Entity and the attributes of
the Customer Class.
Customer Entity Customer Class