What is the difference between DAO, RDO and ADO?

Hi,

What is the difference between DAO, RDO and ADO?

Direct Access Objects(DAO)
RDO(Remote Data Objects)
ActiveX Data Objects (ADO)

DAO is really old and was really meant for interacting with MS Access.
RDO came next. It was more flexible but it still old and crusty by today's
standards. ADO came next and allowed all kinds of data sources (often times by using ODBC). ADO was great, but not very scalable and it was based on old COM technologies.
Thus, ADO.NET came along and that is what all modern developers
use. It is currently the best solution around for nearly any kind of data needs.

DAO is old style, dont use it. It is the original data connector. RDO was the next generation, mostly used for connections to SQL servers, but not used heavily. ADO is the way to go. It is support and is Microsofts primary system for connecting to databases. The same code can be used in almost all the VBscript systems out there including ASP pages. You could learn about the others, but they will just be learning the past. Just my advice.

DAO, RDO, ADO and OLE DB are data access methods that all accomplish exactly the same task.

DAO - Data Access Objects (1-tier)
Allow VB applications to talk to a database (the JET Engine) via ODBC. DAO was Microsoft's first object oriented solution for the manipulation of databases using the Jet Database Engine. The JET engine duplicates the functionalities of ODBC, and thus does not add much value. As the JET engine is generic, many of Oracle's features would not be accessible. Microsoft is phasing out this method.

RDO - Remote Data Objects (2-tier)
Allow VB applications to talk to a relational database (various Relational DBMSs) via ODBC. RDO is an interface to remote RDBMS via OBDC. One needs the Enterprise Edition of Visual Basic to use RDO. Microsoft is encouraging developers to migrate their RDO programs to ADO and OLE-DB.

ADO - ActiveX Data Objects (1 to n-tier)
Allow VB/Other Web Tools (Browsers) to interface with different kinds of data sources. ADO is a more recent Microsoft Data Access technology designed to replace DAO and RDO. ADO is designed to be simpler to use and more powerful than DAO/RDO. Serves an interface to Microsoft's new OLE-DB technology (thinner than ODBC). Can be used to access all sorts of "non traditional data" (e.g., web pages/documents, etc.).

OLE DB data provider
OLE DB is Microsoft's successor to ODBC that utilizes a set of COM interfaces for accessing and manipulating of data. Oracle implemented OLE DB as part of their "Oracle Provider for OLE DB" client software. It provides interface for both data-consuming applications and database providers. OLE DB is considered a thin middle layer which provides better data access performance.