The DataSet class in ADO.Net operates in an entirely disconnected nature.
It is used in disconnected architecture. It does not require a open or active connection to the database. It stores record of one or more data tables.
It works as a bridge between DataSet and Database.
ADO.NET DataReader object is used for accessing data from the data source.
The ADO.NET SqlCommand class in C# is used to store and execute the SQL statement against the SQL Server database.