Here I am gonna explain about how to checking the user authentication against user sql server database.

Step1:

Creating the very simple stored procedure for checking the user is authenticated one or not using below sql query.

create  procedure [dbo].[SP_Authentication]

@username  varchar(250),

@password  varchar(250)

as

begin

declare @count int

if  exists (select * from  userregister where u_name=@username  and u_password=@password )

begin

set @count = 1

end

else

begin

set @count=-1

end

select @count as returnvalue

end

Step 2:

Write a below c# code for checking the user is authenticated one or not.

  using (SqlConnection con = new SqlConnection(connectionstring))

        {

            con.Open();

            SqlCommand cmd = new SqlCommand("SP_Authentication", con);

            cmd.CommandType = CommandType.StoredProcedure;

            string password=FormsAuthentication.HashPasswordForStoringInConfigFile(TextBox2.Text, "SHA1");

            cmd.Parameters.Add("@username",TextBox1.Text);

            cmd.Parameters.Add("@password", password);

            int flag = (int)cmd.ExecuteScalar();

            if (flag == 1)

            {

                FormsAuthentication.RedirectFromLoginPage(TextBox1.Text, false);

            }

            else

            {   //not authenticated user

                Label1.Text = "Invalid User";

            }

            con.Close();

        }

 Output

                              

                                                            Thank you guys........!