connection string in asp.net

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <configSections>
    <sectionGroup name="applicationSettings" type="System.Configuration.ApplicationSettingsGroup, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" >
    </sectionGroup>
  </configSections>
  <appSettings>
         
  </appSettings>
  <connectionStrings>
    <add name="ConnectionString" providerName="System.Data.SqlClient" connectionString="pooling=true; Connect Timeout=30; packet size=4096;user id=username;data source=serverip;persist security info=True;initial catalog=databasename;password=password"/>
  </connectionStrings>
  </configuration>

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

namespace Microsoft.AdoNet.DataSetDemo
{
    class NorthwindDataSet
    {
        static void Main()
        {
            string connectionString = GetConnectionString();
            ConnectToData(connectionString);
       

        private static void ConnectToData(string connectionString)
        {
            //Create a SqlConnection to the Northwind database.
            using (SqlConnection connection =
                       new SqlConnection(connectionString))
            {
                //Create a SqlDataAdapter for the Suppliers table.
                SqlDataAdapter adapter = new SqlDataAdapter();

                // A table mapping names the DataTable.
                adapter.TableMappings.Add("Table", "Suppliers");

                // Open the connection.
                connection.Open();
                Console.WriteLine("The SqlConnection is open.");

                // Create a SqlCommand to retrieve Suppliers data.
                SqlCommand command = new SqlCommand(
                    "SELECT SupplierID, CompanyName FROM dbo.Suppliers;",
                    connection);
                command.CommandType = CommandType.Text;

                // Set the SqlDataAdapter's SelectCommand.
                adapter.SelectCommand = command;

                // Fill the DataSet.
                DataSet dataSet = new DataSet("Suppliers");
                adapter.Fill(dataSet);

                // Create a second Adapter and Command to get
                // the Products table, a child table of Suppliers.
                SqlDataAdapter productsAdapter = new SqlDataAdapter();
                productsAdapter.TableMappings.Add("Table", "Products");

                SqlCommand productsCommand = new SqlCommand(
                    "SELECT ProductID, SupplierID FROM dbo.Products;",
                    connection);
                productsAdapter.SelectCommand = productsCommand;

                // Fill the DataSet.
                productsAdapter.Fill(dataSet);

                // Close the connection.
                connection.Close();
                Console.WriteLine("The SqlConnection is closed.");

                // Create a DataRelation to link the two tables
                // based on the SupplierID.
                DataColumn parentColumn =
                    dataSet.Tables["Suppliers"].Columns["SupplierID"];
                DataColumn childColumn =
                    dataSet.Tables["Products"].Columns["SupplierID"];
                DataRelation relation =
                    new System.Data.DataRelation("SuppliersProducts",
                    parentColumn, childColumn);
                dataSet.Relations.Add(relation);
                Console.WriteLine(
                    "The {0 DataRelation has been created.",
                    relation.RelationName);
           
       

        static private string GetConnectionString()
        {
            // To avoid storing the connection string in your code,
            // you can retrieve it from a configuration file.
            return "Data Source=(local);Initial Catalog=Northwind;"
                + "Integrated Security=SSPI";