Connection to the database from web app to retrieve and modify data - sql-server

Question

I have created a web app and later created a SQL Server instance to which I added an already existing database from my local machin to Azure SQL Server. The database, tables and the data can be viewed in it.
However, my web app consists of web forms like
login page
signup page
change password
where it checks with the database if the data exists or not else modifies the data there.
I've changed the connection string that's provided by the database in the azure portal. Yet it doesn't work and it shows an error:
The resource you are looking for has been removed, had its name changed, or is temporarily unavailable
Now I have no idea how to resolve it.
And I was expecting some further process like
If I see for login creds' it checks within the database if the creds' exist and then show either an alert saying 'no such username or password' or 'redirects to another page'.

Answer 1

I created empty asp.net web page in visual studio and added new web form
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Right click on the webapp and select add option and click on new item.
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I added new webform to the webapp.
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I created login page in new web form
Login page:
I created database in azure sql and created table with user details.
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I connected azure sql database to the webapp.
Process for add Azure sql server to the web app:
open SQL Server object explorer in visual studio click on add sql server.
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Click on azure and selected my server and enter the password connected to azure sql db.
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My azure sql server is connected successfully to my webapp.
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In web.config file I add the connection string of my sql server
<connectionStrings>
<add name="dbconnection" connectionString="Data Source=<serverName>;Initial Catalog=<dbName>;Integrated Security=True"/>
</connectionStrings>
I write the below code for login in error and redirect to the page of when login success in my login page:
using System;
using System.Data;
using System.Data.SqlClient;
using System.Web.Configuration;
namespace login_page
{
public partial class WebForm1 : System.Web.UI.Page
{
SqlConnection SQLConn = new SqlConnection("Data Source = C1ML63563-MS; Initial Catalog=db; Integrated Security = True");
protected void Button1_Click(object sender, EventArgs e)
{
String constr = WebConfigurationManager.ConnectionStrings["dbconnection"].ConnectionString;
SqlConnection sqlConn = new SqlConnection(constr);
try
{
sqlConn.Open();
SqlCommand cmd = new SqlCommand("select count(*) from userdb where UserName ='" + txtusername.Text + "' and Password ='" + txtpassword.Text + "'", sqlConn);
SqlDataAdapter adapter = new SqlDataAdapter(cmd);
DataTable DT = new DataTable();
adapter.Fill(DT);
cmd.ExecuteNonQuery();
if (DT.Rows[0][0].ToString() == "1")
{
Response.Write("<script>alert('Login successfully')</script");
Response.Redirect("~/web.aspx");
}
else
{
Response.Write("<script>alert('error in login')</script");
}
}
catch(Exception ex)
{
Response.Write(ex.Message);
}
}
}
}
I run the web app It successfully run.
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Login page:
If I enter wrong details I got error in login pop-up.
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If I enter Correct details which are already stored in database, it is redirecting to another page below code is used for redirect of another page:
Response.Redirect("~/web.aspx");
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