php - 带有 LIMIT 别名的 SQL SUM 返回 "undefined index"

Question

有人能告诉我这段代码有什么问题吗？页面返回一个:

Notice: Undefined index: totlvlown in /home/admin/domains/reincarnationgame.com/public_html/alliancespar.php on line 82

我的代码是:

$query = $dbcon->prepare('SELECT sum(level) FROM (SELECT player.level FROM player WHERE player.alliance = '.$alliance.' ORDER BY player.level DESC LIMIT '.$playersown.') AS totlvlown');
$query->execute();
$row = $query->fetch(PDO::FETCH_ASSOC);
$totallvlown = $row['totlvlown'];

变量 $alliance 和 $playersown 是简单整数。稍后将替换为绑定(bind)值。

我是子查询的新手，似乎无法让它工作。我尝试将 AS 部分移到 FROM 部分之前，但这只是告诉我所有表都需要别名。

Answer 1

尝试这个解决方案因为我认为你必须先开始表名，然后开始别名，以便别名级别可以被sum函数识别 >

$queryalliancelvlown = $dbcon->prepare('SELECT player level sum(level)
FROM 
(
  SELECT player.level
  FROM player
  WHERE player.alliance = '.$alliance.' 
  ORDER BY player.level DESC LIMIT '.$playersown.'
) AS totlvlown');