ถามเรื่องการเขียนไฟล์ติดต่อกับฐานข้อมูล

<?php
$dbhost = "localhost";
$dbuser = "root";
$dbpass = "1234";
$dbname = "sa";

if(!($conn = mysql_connect($dbhost,$dbuser,$dbpass)))
{
die("Couldn't establish connection to Mysql,database!");
}

if(!mysql_select_db($dbname))
{
die("Couldn't connect to database $dbname!");
}
mysql_query("SET NAMES UTF8");
?>

ผมเอา session_start ไปไว้บรรทัดแรกหมดทุกไฟล์แล้วครับ

connect.php

โค๊ด:

<?php
	$dbhost = "localhost";
	$dbuser = "root";
	$dbpass = "1234";
	$dbname = "sa";

if(!($conn = mysql_connect($dbhost,$dbuser,$dbpass)))
	{
		die("Couldn&#39;t establish connection to Mysql,database!");
	}

if(!mysql_select_db($dbname))
	{
		die("Couldn&#39;t connect to database $dbname!");
	}
	mysql_query("SET NAMES UTF8");
?>

โค๊ด:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Login</title>
<link rel="stylesheet" type="text/css" href="bootstrap.css" />
</head>

<body>

<form  name="form1" method="post"  action="check_login.php" class="form-search">
  <br><center>Login</center><br>
  <table border="0" style="width: 300px" align="center">
    <tbody>
      <tr>
        <td> &nbsp;Username</td>
        <td>
          <input name="txtUsername" type="text" id="txtUsername" class="input-medium search-query">
        </td>
      </tr>
      <tr>
        <td> &nbsp;Password</td>
        <td><input name="txtPassword" type="password" id="txtPassword" class="input-medium search-query">
        </td>
      </tr>
    </tbody>
  </table>
  <br>
  <center><input type="submit" name="Submit" value="Login" class="btn"></center>
</form>
</body>
</html>

check_login.php

โค๊ด:

<?
	session_start();
	require_once("connect.php");
	$strSQL = "SELECT * FROM member WHERE Username = '".trim($_POST['txtUsername'])."' 
	and Password = '".trim($_POST['txtPassword'])."'";
	$objQuery = mysql_query($strSQL);
	$objResult = mysql_fetch_array($objQuery);
	
	echo $strSQL;
	if(!$objResult)
	{
			echo "Username and Password Incorrect!";
	}
	else
	{
			$_SESSION["UserID"] = $objResult["UserID"];
			$_SESSION["Status"] = $objResult["Status"];

			session_write_close();
			
			if($objResult["Status"] == "ADMIN")
			{
				header("location:admin_page.php");
			}
			else
			{
				header("location:user_page.php");
			}
	}
	mysql_close();
?>

admin_page.php

โค๊ด:

<?
	session_start();
	if($_SESSION['UserID'] == "")
	{
		echo "Please Login!";
		exit();
	}

	if($_SESSION['Status'] != "ADMIN")
	{
		echo "This page for Admin only!";
		exit();
	}	
	
	require_once("connect.php");
	$strSQL = "SELECT * FROM member WHERE UserID = '".$_SESSION['UserID']."' ";
	$objQuery = mysql_query($strSQL);
	$objResult = mysql_fetch_array($objQuery);
?>
<html>
<head>
<title></title>
</head>
<body>
  Welcome to Admin Page! <br>
  <table border="1" style="width: 300px">
    <tbody>
      <tr>
        <td width="87"> &nbsp;Username</td>
        <td width="197"><?=$objResult["Username"];?>
        </td>
      </tr>
      <tr>
        <td> &nbsp;Name</td>
        <td><?=$objResult["Name"];?></td>
      </tr>
    </tbody>
  </table>
  <br>
  <a href="edit_profile.php">Edit</a><br>
  <br>
  <a href="logout.php">Logout</a>
</body>
</html>