php - IF 语句未按预期运行

Question

如果用户已登录，我想显示用户的全名。如果没有，则应显示文本“登录”。

这是我目前所拥有的:

session_start();

$session = $_SESSION['username'];

include "config.php";

$sql = mysql_query("SELECT * from user");    
while($d=mysql_fetch_array($sql))
{
    if($d['status']=='online' and $_SESSION['username'] == $d['username'])
    {
        $full_names = $d['full_name'];

        echo $full_names;
    }
    else
    {
        echo "Login";
    }
}

有什么想法吗？

Answer 1

您应该使用 SQL WHERE(如@ThiefMaster 所述)，但只是为了回答您的问题:

$full_names = false;
while($d=mysql_fetch_array($sql)) {
    if($d['status']=='online' and $_SESSION['username'] == $d['username']) {
        $full_names = $d['full_name'];

        echo $full_names;
    }
}

if(!$full_names) {
  echo "Login";
}