ADO is active x data object. It is used to access database with
the help of data controls and objects as well. it is an extended
form of RDO and DAO.
RDO is remote data object which is used to access server site
data. data in this case reside on the sql server. and we use sql
queries to access data. in this we write a sql command and then squ
server processes it and gives back the result.
DAO is data access object. it is used to access data with the
help of program and some data controls. it provides an extention to
data controls and data bound controls. DAO helps in accessing data
with various conditions or quries.