what is the difference between data adapter and data reader?

Question

What is the difference between data adapter and data reader?

Answer 1

Here is a nice article on the above topic: Difference Between DataReader, DataSet, DataAdapter and DataTable in C#

Key differences in simple terms:

Unlike classic ADO, which was primarily designed for tightly coupled client/server systems,ADO.NET was built with the disconnected world in mind, using DataSets/DataAdapter.

• DataAdapter follows connectionless-oriented architecture which simply means you need not necessarily be connected to a data-source whereas DataReader is a connection-oriented architecture which means it needs an active connection to a data-source for it to operate.
• DataAdapter is an intermediate layer/ middleware which acts a bridge between the DataSet and a Database whereas DataReader provides forward-only, read-only access to data using a server-side cursor (simply put it is ued to read the data).
• Using DataSet we can manipulate and update a DataSet's contents while disconnected from the Datasource and send any modified data back for processing using a related DataAdapter whereas DataReader can only read data from a Database & cannot modify it.
• DataAdapter object is used to read the data from database and populates that data to DataSet whereas DataReader simply reads the data using the Read() method.
• DataAdapter is comparatively slower whereas using DataReader can increase application performance both by retrieving data as soon as it is available, and (by default) storing only one row at a time in memory, reducing system overhead.