PHP while 循环返回空结果

Question

$connect_status = "SELECT connected_to_id FROM tbl_connect WHERE user_id = 
{$_SESSION['user_id']}";

$exec_connstatus_query = mysql_query($connect_status, $db_connect);

while($check_status = mysql_fetch_array($exec_connstatus_query))
{   
  if ($check_status['connected_to_id'] == $profileid)
  {
    echo "{$check_status['connected_to_id']}";
  }
  else
  {
    echo "fail";
  }
}

这段代码已经困扰了我 3 个小时。即使在这种情况下，问题仍然存在:

if ($check_status['connected_to_id'] == $profileid)

返回 false，当 else 语句执行时我看不到“失败”。有什么想法吗？

Answer 1

mysql_query() 出错时返回 FALSE，并且循环根本不会执行。如果 $_SESSION['user_id'] 不是数字，就会发生这种情况。为什么不只是

$connect_status = "SELECT connected_to_id FROM tbl_connect WHERE user_id ='$_SESSION[user_id]'";

如果没有(更多)行，则 mysql_fetch_array() 返回 FALSE。如果 tbl_connect 中不存在您的 session ，则循环将不会执行。难道你不想要这样的东西:

$connect_status = "SELECT connected_to_id FROM tbl_connect 
                   WHERE user_id ='$_SESSION[user_id]' LIMIT 1";
$exec_connstatus_query = mysql_query($connect_status, $db_connect);
if( ($check_status = mysql_fetch_array($exec_connstatus_query)) && 
    ($check_status['connected_to_id'] == $profileid) ) {
    echo "{$check_status['connected_to_id']}";
} else {
    echo "fail";
}