DB Connection code in Dotnet for Begineers

It should be in aspx.cs
using System.Data;
using System.Data.SqlClient;
using System.Configuration;

string connectionInfo = ConfigurationManager.ConnectionStrings["PDFConnectionString"].ConnectionString;
// Creates Db Connections
SqlConnection myConnection = new SqlConnection(connectionInfo);


myConnection.Open();
objCmd = new SqlCommand("SELECT OrderNumber FROM [dbo].tblEorder WHERE eOrderID = (SELECT eOrderID FROM [dbo].tblTempToken WHERE TempToken='" + strPDFToken + "')", myConnection);
ObjDR = objCmd.ExecuteReader();

//Get PURLtoken(OrderNumber) for the requested form
while (ObjDR.Read())
{
purltoken = ObjDR["OrderNumber"].ToString();
// Return to Main URL. - Executes client side script
string jScriptString;
/*jScriptString = "<script> parent.window.close(); \n" +
"window.opener.close(); window.opener.opener.location.href = " + "'http://bltrdevm58072/eproducts360/BRWSDemo/main.html?token=" + purltoken + "&formpage=true'";
jScriptString += " </script>";*/
jScriptString = "<script> var objWin=window.opener; parent.window.close(); \n" +
"window.opener.close();objWin.opener.location.href = " + "'http://bltrdevm58072/eproducts360/BRWSDemo/main.html?token=" + purltoken + "&formpage=true'";
jScriptString += " </script>";
ClientScript.RegisterClientScriptBlock(this.GetType(), "clientScript", jScriptString);
}

Web.config
<connectionStrings>
<add name="ApplicationServices" connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|\aspnetdb.mdf;User Instance=true" providerName="System.Data.SqlClient"/>
<add name="PDFConnectionString" connectionString="Data source=blitswargd01\sql81;User ID=cf;Password=powercf;Initial Catalog=E360MTJan;"/>

</connectionStrings>