Modify DataTable: insert data to database table

   
 
using System;
using System.Data;
using System.Data.SqlClient;

   class ModifyDataTable
   {
      static void Main()
      {
         string connString = "server=(local)SQLEXPRESS;database=MyDatabase;Integrated Security=SSPI";
         string sql = @"select * from employee";

         SqlConnection conn = new SqlConnection(connString);

         try {
            SqlDataAdapter da = new SqlDataAdapter();
            da.SelectCommand = new SqlCommand(sql, conn);

            DataSet ds = new DataSet();   
            da.Fill(ds, "employee");

            DataTable dt = ds.Tables["employee"];

            dt.Columns["firstname"].AllowDBNull = true;

            dt.Rows[0]["FirstName"] = "Joe";

            DataRow newRow = dt.NewRow();
            newRow["firstname"] = "Roy";
            newRow["lastname"] = "Beatty";
            dt.Rows.Add(newRow);

            foreach (DataRow row in dt.Rows)
            {
               Console.WriteLine("{0} {1}",
                  row["firstname"].ToString().PadRight(15),
                  row["lastname"].ToString().PadLeft(25));
            }
            
         } catch(Exception e) {

            Console.WriteLine("Error: " + e);

         } finally {

            conn.Close();

         }
      }  
   }