Updating Multiple Rows

How would I update a table where id = a list of ids?
Do I need to parse the string idList? I am being passed a comma seperated string of int values from a flex application.
example: 1,4,7,8 
 Any help much appreciated
Barry 
 1 [WebMethod]
2 public int updateFirstName(String toUpdate, String idList)
3 {
4 SqlConnection con = new SqlConnection(connString);
5
6 try
7 {
8 con.Open();
9 SqlCommand cmd = new SqlCommand();
10 cmd.Connection = con;
11 cmd.CommandText = "UPDATE tb_staff SET firstName = @firstName, WHERE id = @listOfIDs";
12
13
14
15 SqlParameter firstName = new SqlParameter("@firstName", toUpdate);
16 SqlParameter listOfIDs= new SqlParameter("@listOfIDs", idList);
17
18
19
20 cmd.Parameters.Add(firstName);
21 cmd.Parameters.Add(listOfIDs);
22
23 int i = cmd.ExecuteNonQuery();
24 con.Close();
25 return 1;
26
27 }
28 catch
29 {
30 return 0;
31 }
32 }
33
34