Asp. NET connection Database configuration file

Web.config<?xml version= "1.0" encoding= "Utf-8"?><!--For more information about how to configure an ASP. NET application, go to http://go.microsoft.com /fwlink/? linkid=169433--><configuration> <system.web> <compilation debug= "false" targetframework= "4.5" /> The using System.Configuration is then added to the namespace; private string connectionString = configurationsettings.appsettings["connectionString"].    ToString (); private string connectionString = configurationmanager.appsettings["connectionString"].    ToString (); protected void Page_Load (object sender, EventArgs e) {if (!this.        IsPostBack) {filllist ();        }} private void Filllist () {String selectsql = "SELECT * from Stu";        SqlConnection con = new SqlConnection (connectionString);        SqlCommand cmd = new SqlCommand (Selectsql,con);        SqlDataAdapter adapter = new SqlDataAdapter (cmd);        DataSet ds = new DataSet (); try {con.            Open (); Adapter.            Fill (ds, "Students"); This. Gridview1.datasource = ds. tables["Students"].            DefaultView; This.        Gridview1.databind ();        } catch (Exception err) {throw err; }    }}

　　

ASP. NET connection Database configuration file