这个php登陆代码总是不成功。请看看这是哪里有问题 ?
<?php
session_start();
$conn=mysql_connect("localhost","admin","admin") or die ("数据库链接错误".mysql_error());
mysql_select_db('member',$conn) or die("选择数据库有错".mysql_error());
define(ALL_PS, "php123");
if($_POST[submit])
{
$username=str_replace(" ","",$_POST[username]);
$sql="select * from user_list where 'username' ='$username'";
$query=mysql_query($sql);
$ps = $us ? md5($_POST[password].ALL_PS)==$row[password] : FALSE;
if($ps){
$_SESSION[uid]=$row[uid];
$_SESSION[user_shell]=md5($row[username].$row[password].ALL_PS);
echo "ok";
}else{
echo "no";
}
}
?>
<form action="" method="post"">
用户:<input type="text" name="user" /><br />
密码:<input type="password" name="password" /><br />
<input type="submit" name="submit" value="tttt" />
</form>
if($_POST['submit'])
{
$username=str_replace(" ","",$_POST['username']);
$sql="select * from user_list where `username` ='$username'";
$query=mysql_query($sql);
$row = mysql_fetch_assoc($query);
$ps = $row['username'] ? md5($_POST['password'].ALL_PS)==$row[password] : FALSE;