how to insert function value in coloumn

i have created an sql function  in database name datainfo and table name as book
create function[dbo].[book_id](@id int) return char(12) as begin return 'bkooID'+right('00000'+convert(varchar(10),@id),5) end
 i want to insert this value in column book_id using asp.net on button click.. 
please write sqlcommand for this  
this is my sqlconnection code SqlConnection con; SqlCommand cmd; string str = ConfigurationManager.ConnectionStrings["connect"].ConnectionString; protected void btnSubmit_Click(object sender, EventArgs e) { SqlConnection con = new SqlConnection(str); }