Login page code

Login.aspx

<table style="margin: auto; margin-top: 20px; font-family: Arial; font-size: 13px;"

                        cellpadding="5px" cellspacing="5px">

                        <tr>

                            <td colspan="2" align="center" style="text-decoration: underline;">

                                User Login

                            </td>

                        </tr>

                        <tr>

                            <td colspan="2">

                                <asp:Label ID="lblUserMessage" runat="server" ForeColor="Red"></asp:Label>

                            </td>

                        </tr>

                        <tr>

                            <td>

                                Username:

                            </td>

                            <td>

                                <asp:TextBox ID="txtuser" runat="server"></asp:TextBox>

                            </td>

                        </tr>

                        <tr>

                            <td>

                                Password:

                            </td>

                            <td>

                                <asp:TextBox ID="txtpass" runat="server" TextMode="Password"></asp:TextBox>

                            </td>

                        </tr>

                        <tr>

                            <td>

                            </td>

                            <td>

                                <asp:Button ID="btnsubmit" runat="server" Text="Login" OnClick="btnsubmit_Click" />

                            </td>

                        </tr>

                        <tr>

                            <td align="left">

                                <asp:LinkButton ID="cmdUserForget" runat="server" CssClass="normal-link"

                                    onclick="cmdUserForget_Click">Forget password</asp:LinkButton>

                            </td>

                            <td align="right">

                                for register <a href="registration.aspx" class="normal-link">Click here</a>

                            </td>

                        </tr>

                    </table>

Login.aspx.cs(Code Behind)

protected void btnsubmit_Click(object sender, EventArgs e)

    {

        sqlquery = "select * from tablename where email_id='"+txtuser.Text+"' and password='"+txtpass.Text+"'";

SqlConnection con = new SqlConnection(_ConnectionString);
            con.Open();
            SqlTransaction trans = con.BeginTransaction();
SqlCommand cmd = con.CreateCommand();
            cmd.Transaction = trans;
DataSet ds = new DataSet();
              

        try

        {

             SqlDataAdapter da = new SqlDataAdapter(cmd);
                da.Fill(ds);

        }

        catch (Exception ex)

        {

           

        }

        if (ds != null & ds.Tables[0].Rows.Count > 0)

        {

            if (ds.Tables[0].Rows[0]["usertype"].ToString() == "1")

            {

                Session["userid"] = ds.Tables[0].Rows[0]["userid"].ToString();

                Session["username"] = ds.Tables[0].Rows[0]["username"].ToString();

            }

            else

            {

               

            }

        }

        else

        {

            Response.Redirect("login.aspx");

        }

    }