[c#] Uploading an Excel sheet and importing the data into SQL Server database

You are dealing with a HttpPostedFile; this is the file that is "uploaded" to the web server. You really need to save that file somewhere and then use it, because...

...in your instance, it just so happens to be that you are hosting your website on the same machine the file resides, so the path is accessible. As soon as you deploy your site to a different machine, your code isn't going to work.

Break this down into two steps:

1) Save the file somewhere - it's very common to see this:

string saveFolder = @"C:\temp\uploads"; //Pick a folder on your machine to store the uploaded files

string filePath = Path.Combine(saveFolder, FileUpload1.FileName); 

FileUpload1.SaveAs(filePath);

Now you have your file locally and the real work can be done.

2) Get the data from the file. Your code should work as is but you can simply write your connection string this way:

string excelConnString = String.Format("Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0};Extended Properties="Excel 12.0";", filePath);

You can then think about deleting the file you've just uploaded and imported.

To provide a more concrete example, we can refactor your code into two methods:

    private void SaveFileToDatabase(string filePath)
    {
        String strConnection = "Data Source=.\\SQLEXPRESS;AttachDbFilename='C:\\Users\\Hemant\\documents\\visual studio 2010\\Projects\\CRMdata\\CRMdata\\App_Data\\Database1.mdf';Integrated Security=True;User Instance=True";

        String excelConnString = String.Format("Provider=Microsoft.ACE.OLEDB.12.0;Data Source={0};Extended Properties=\"Excel 12.0\"", filePath);
        //Create Connection to Excel work book 
        using (OleDbConnection excelConnection = new OleDbConnection(excelConnString))
        {
            //Create OleDbCommand to fetch data from Excel 
            using (OleDbCommand cmd = new OleDbCommand("Select [ID],[Name],[Designation] from [Sheet1$]", excelConnection))
            {
                excelConnection.Open();
                using (OleDbDataReader dReader = cmd.ExecuteReader())
                {
                    using(SqlBulkCopy sqlBulk = new SqlBulkCopy(strConnection))
                    {
                        //Give your Destination table name 
                        sqlBulk.DestinationTableName = "Excel_table";
                        sqlBulk.WriteToServer(dReader);
                    }
                }
            }
        } 
    }


    private string GetLocalFilePath(string saveDirectory, FileUpload fileUploadControl)
    {


        string filePath = Path.Combine(saveDirectory, fileUploadControl.FileName);

        fileUploadControl.SaveAs(filePath);

        return filePath;

    }

You could simply then call SaveFileToDatabase(GetLocalFilePath(@"C:\temp\uploads", FileUpload1));

Consider reviewing the other Extended Properties for your Excel connection string. They come in useful!

Other improvements you might want to make include putting your Sql Database connection string into config, and adding proper exception handling. Please consider this example for demonstration only!