Insert query in C# for GETDATE()

May i know how to access GETDATE() value using insert query in C# (db connection), For Singe Cell in a row..
Every time i login into the page..Instead update, i use insert query to display time in gridview column .. If i use update query i cant get list of search values filtered using date
I have four columns(one primary too) in that i want to change only fourth cell Getdate(). value using insert query its challenging i tried more cant get result
primarycol. col1 col2 col3 Date(col4) 12345 aaa 4000.00 a121 2014-04-14 17:08:16.437 67890 bbb 3500.00 @121 2014-04-14 17:08:22.873 112233 ccc 2000.00 12345 2014-04-14 17:07:23.700 445566 ddd 6000.00 6789 2014-04-14 15:25:29.857 SqlCommand cmd = new SqlCommand(("Insert into tablename (Date) values('" + DateTime.N ...