Data access mechanism: – Visual basic support three different types of data access mechanism. They are –

  1. DAO: – DAO stand far data access object. It allows user to access the jet database engine, as supplied with Microsoft access. Because it was easy to use, it quickly became one of the most popular methods of accessing database, however, it is limited to access database.
  2. RDO: – RDO stand for remote data object. It was partially design to overcome the complexity issue of ODBC. ODBC stands for open database connectivity. It was design to allow programmer to connect to a verity of data bases, but using a single method. It is burden because only one technique needed to learnt, and it allow the data base to be change. If required, for instance, when moving from access to SQL server. It is use for DAO allowed access database to link to other database. Its one disadvantage is it complexity.
  3. ADO: – ADO stand for ActiveX data object. ADO was design to combine all the best feature of DAO and RDO, as well as meeting the requirement of the new programming word, spicily the internet. It takes advantage of the data store idea, so it can get data from many different places. ADO was a new database connection frame work called OLEDB (Object Linking and Embedding Database) which allows fast and more flexible access to multiple data provider.