Is MS Access a Relational or Object Oriented Database?

[YunqHero]

There is a wealth of information on the Web, but I cannot find the answer to my question. I understand that Access has all the qualities of a Relational Database, however, it performs like an Object Oriented Database. My question is what type of database is it? OO or Relational ? Feel free to provide some key differences, I understand the basics.

[ssanfu]

As I understand it, Access is an event driven RDMS - Relational Database Management System as opposed to dBase 3+, a flat (non-Relational) database that is (was) procedural driven.

While Access has Class Modules, it is not truly OOP because it doesn't support true inheritance. See http://www.caug.com/caug-classes.htm

Here is an article on classes by Albert Kallal. http://www.kallal.ca/Articles/WhyClass.html

My $0.02....

[Rod]

Steve is correct in all he writes; there is nothing OOP about the database; you cannot even save an object instance but have to 'rebuild' all instances from scratch every time you open the database.

However Access itself is an OOP application. All Access 'things' are object classes and instances; for example, the form you design is a class inherited from the generic Access form class and when you open the designed form it is an instance of your designed class.

As far as the VBA user class modules are concerned, Access does not inherit boilerplate code, only the property/method name and type, common code therefore has to be repeatedly specified in all inherited classes which is very tedious. It is not possible to implement some of the classic OOP class patterns; for example, I have yet to find a way of implementing a 'Singleton.' (I use a standard module for this.) Recently I was involved in answering a question on this forum where the poster wanted to restrict a property/method's availability to the instantiating object and only the instantiating object. It cannot be done (in a foolproof manner) although I suspect it is possible in other languages.

In summary I would propose that the JET database is a relational database but that Access (in fact all Office applications) and VBA follow OOP priciples, a fact you should bear in mind when coding VBA.

[ButtonMoon]

MS Access is certainly neither of those things. MS Access is an application development tool which can be and is used to develop applications for a variety of different databases - whether they happen to be relational or non-relational.

There isn't necessarily a widely accepted definition of what constitutes an Object Oriented DBMS. Probably the most commonly agreed and logically coherent explanation is that a DBMS is Object Oriented if it supports type-inheritence. That might just as well be a relational DBMS as a non-relational one. So an OO DBMS doesn't have to be something different from a RDBMS because the two concepts are entirely orthogonal.

[Rod]

Sorry I disagree. The JET (Joint Engine Technology) which is a major component of Access is a relational database management system (RDBMS), actually a very, very good small scale RDBMS. To dismiss Access as 'an application development tool' is to ignore over half its functionality. JET also has provision for open database connectivity (ODBC) workspaces which when used (especially with the ADO object model) to communicate with other compliant databases (Oracle, SQL Server, etc.) do relegate Access to the role of a front-end facility, but even in this situation it is possible for Access to also contain its own JET database.

Whatever definition you use, there is nothing object oriented about JET; it is relational at the data item level and makes no provision for the management of object instances.