Easy way to update Excel data to SQL Server
You coud either use BULK INSERT directly in SQL Server Management Studio like this:

BULK INSERT [DataBase].[dbo].YourTable
FROM 'filepath'
WITH
(
    Firstrow = 1,
    Fieldterminator=';',
    Rowterminator='\n',
    Codepage = 'ACP'
)


For Excel-Files (.xls) you can use this:

SELECT * INTO YourTable FROM OPENROWSET('Microsoft.Jet.OLEDB.4.0',
'Excel 8.0;Database=YourFilePath', [ExcelSheet$])


You may have to replace the 8.0 with your current office version (8.0 is for Office 2000, 14.0 is for Office 2010, for example).

There's also SqlBulkCopy in C#.

If you don't want to import all columns, I suggest you write a small program, load the file into a DataTable, drop all the columns you don't need and then use SqlBulkCopy