Import Updated Data into Sql Database

using System;
using System.Data;
using System.Data.SqlClient;
   class PropagateChanges {
      static void Main(){
         string connString = "server=(local)\\SQLEXPRESS;
         database=MyDatabase; Integrated Security=SSPI";
         string query = @"select * from employees ";
         string update = @"update employees set firstname = @firstname where id = @id";
         SqlConnection conn = new SqlConnection(connString);
         try {
            SqlDataAdapter da = new SqlDataAdapter();
            da.SelectCommand = new SqlCommand(query, conn);
            DataSet ds = new DataSet();   
            da.Fill(ds, "employees");
            DataTable dt = ds.Tables["employees"];
            dt.Rows[0]["firstname"] = "ABC";
            foreach (DataRow row in dt.Rows){
               Console.WriteLine(
                  "{0} {1}",
                  row["firstname"].ToString().PadRight(15),
                  row["lastname"].ToString().PadLeft(25));
            }
            // Update employees
            SqlCommand cmd = new SqlCommand(update, conn);
            cmd.Parameters.Add("@firstname",SqlDbType.NVarChar,15, "firstname");
            SqlParameter parm = cmd.Parameters.Add("@id",SqlDbType.Int,4,"id");
            parm.SourceVersion = DataRowVersion.Original;
            da.UpdateCommand = cmd;
            da.Update(ds, "employees");
         } catch(Exception e) {
            Console.WriteLine("Error: " + e);
         } finally {
            conn.Close();
         }
      }  
   }