CREATE PROCEDURE logincheck
(
@u varchar(50),
@p varchar(100)
)
as
declare @ap varchar(50)
select @ap=password from tbuser where loginid=@u
if @ap is null
return -1
else
if @ap=@p
return 1
else
return -2

 private Int32 checkuser(string u, string p)
    {
 SqlConnection con = new SqlConnection();
con.ConnectionString = ConfigurationManager.ConnectionStrings["cn"].ConnectionString;
        con.Open();
        SqlCommand cmd = new SqlCommand("logincheck", con);
        cmd.CommandType = CommandType.StoredProcedure;
        cmd.Parameters.Add("@u", SqlDbType.VarChar, 50).Value = u;
        cmd.Parameters.Add("@p", SqlDbType.VarChar, 50).Value = p;
        SqlParameter p1 = new SqlParameter("ret", SqlDbType.Int);
        p1.Direction = ParameterDirection.ReturnValue;
        cmd.Parameters.Add(p1);
        cmd.ExecuteNonQuery();
        Int32 k;
        k = Convert.ToInt32(cmd.Parameters["ret"].Value);
        cmd.Dispose();
        return k;
    }

Int32 r = checkuser(TextBox1.Text, TextBox2.Text);
        if (r == -1)
        {
            Label1.Text = "Incorrect User Id";
        }
        if (r == -2)
        {
            Label1.Text = "Incorrect Password";
        }
        if (r == 1)
        {
SqlDataAdapter adp = new SqlDataAdapter("select uid, loginid from tbuser where loginid='" + TextBox1.Text + "' and password ='" + TextBox2.Text + "'", ConfigurationManager.ConnectionStrings["cn"].ConnectionString);
            DataSet ds = new DataSet();
            adp.Fill(ds);
            Session["uid"] = ds.Tables[0].Rows[0][0].ToString();
            Session["loginid"] = TextBox1.Text;
            Session["password"] = TextBox2.Text;
            if (TextBox1.Text == "admin")
            {
             Response.Redirect("home.aspx");   //redirect to any desired page
            }
        }
        else
        {
            Label1.Text = "Incorrect User Id / Password ";
        }