Update Database Using The SqlDataAdapter

 Hi,
 I was looking at how to update a database using SqlDataAdapter and I stumbled upon this code snippet from (http://www.java2s.com/Code/CSharp/Database-ADO.net/UpdatedatabaseusingtheSqlDataAdapter.htm):
using System;
using System.Data;
using System.Data.SqlClient;

class Class1{
static void Main(string[] args){
SqlConnection thisConnection = new SqlConnection("server=(local)\SQLEXPRESS;database=MyDatabase;Integrated Security=SSPI");
SqlDataAdapter thisAdapter = new SqlDataAdapter("SELECT ID, FirstName FROM Employee", thisConnection);

SqlCommandBuilder thisBuilder = new SqlCommandBuilder(thisAdapter);

DataSet thisDataSet = new DataSet();

thisAdapter.Fill(thisDataSet, "Employee");

Console.WriteLine("name before change: {0}", thisDataSet.Tables["Employee"].Rows[9]["FirstName"]);

thisDataSet.Tables["Employee"].Rows[1]["FirstName"] = "Inc";

thisAdapter.Update(thisDataSet, "Employee");

Console.WriteLine("name after change: {0}", thisDataSet.Tables["Employee"].Rows[9]["FirstName"]);


}
}I was just wondering, without iteration, how did the line  "thisDataSet.Tables["Employee"].Rows[1]["FirstName"] = "Inc";" managed to know which row it is to update? I tried it on my own application and it worked fine.Any help to assist me in understanding this would be appreciated. Thanks