Question - What is the significance of CommandBehavior.CloseConnection ?
Answer -
To avoid having to explicitly close the connection associated with the command used to create either a SqlDataReader or and OleDbDataReader, pass the CommandBehavior.CloseConnection argument to the ExecuteReader method of the Connection.
dr= cmd.ExecuteReader(CommandBehavior.CloseConnection);
The associated connection will be closed automatically when the Close method of the Datareader is called. This makes it all the more important to always remember to call Close on your datareaders.