Please see my replies inline.
please give me answer of some question
what's dif b/w html server control & web server control?
what is view state?
what is postback?
Control data is sent from the client to the server.
what's diff b/w data grid & data list?
In short, a datalist control is a lightweight datagrid control.
what is index & diff b/w clustered & non clustered index
An index is used to speed up database queries. When a table (for example) is indexed on a certain column, the database server maintains special data structures that can allow quick searching on items in that column. Also visit http://www.sql-server-performance.com/gv_index_data_structures.asp for information on clustered vs non-clustered indices.
can data set work in connected environment?
If you need connected "recordset" functionality, consider DataReader instead.