While relational and object databases use different sets of terms, it is possible to draw parallels between some of the terms:
OODBMS |
RDBMS |
Similar |
Different |
Class |
Table |
Define an entity data structure. |
Class can define fields (static data) and methods, while table can only define static data. |
Object instance |
Tuple |
Represent an instance of data defined in a class or a table. |
Object can hold data of different visibility and references to other objects. Tuple consists of system type data. |
Attribute |
Column |
Define one of the fields in the data definition. |
RDBMS has a preset collection of types, which can be used to define the type of the data in the column. OODBMS can use user-defined types. |
Method |
Stored Procedure |
Define a piece of functionality. |
Method is a characteristic of a class. Stored procedure is a separate object in RDBMS. |
Identity |
Key |
Identify a single object or tuple. |
Object identity makes any object unique independently of the object content. Key imposes a uniqueness of a database object based on the uniqueness of the column values. |
Reference |
Relation |
Link different objects within a database. |
In OODBMS direct object links are used. In RDBMS objects are linked through foreign keys, i.e. identical values in different rows. |
Note, that the above-mentioned terms are similar only to a certain degree; there are some fundamental differences between them.