I have an requirement where user uploads an excel file in this process data from cell is extracted and then saved in database (excel file won't get saved in our application only data is extracted) our application when reads this file then it must read all cells one by one and while processing it should do three important task:

1- If special character is found in excel cell then that row must be ignored and after process is complete it should display that cell data in gridview.

2- There should be not more than four columns in excel file.

3- If complete row data is already found in database then system should ignore that row

While surfing I found few articles which might help you/me in finding the solution:

http://www.aspsnippets.com/Articles/Export-GridView-Data-to-Excel-using-OpenXml-in-ASPNet.aspx

http://www.aspsnippets.com/Articles/Read-and-Import-Excel-Sheet-into-SQL-Server-Database-in-ASP.Net.aspx

http://www.aspsnippets.com/Articles/Read-and-Import-Excel-Sheet-into-ASP.Net-GridView-Control.aspx

http://www.aspsnippets.com/Articles/Read-and-Import-Excel-Sheet-using-ADO.Net-and-C.aspx

http://www.mikesdotnetting.com/article/297/the-best-way-to-import-data-from-excel-to-sql-server-via-asp-net