php/mysql 函数的奇怪行为

Posted 2023-05-09

【中文标题】php/mysql 函数的奇怪行为

【英文标题】：Strange behavior of a php/mysql function

【发布时间】：2014-12-30 02:01:56

【问题描述】：

我正在做一个项目，我必须在其中显示玩家的排行榜。但是当编写下面的代码时，它显示了 2, 4, 6, 8, ... 的排名，而不是奇数排名。谁能告诉我“这有什么问题？”

$query1_string = "CREATE VIEW Leaderboard AS SELECT Name, Points, PhoneNo
                  FROM user ORDER BY Points DESC";
$query2_string = "set @rank = 0";
$query3_string = "SELECT @rank := @rank + 1 as Rank, Name, Points
                  FROM Leaderboard";
$query5_string = "DROP VIEW Leaderboard";

// Doing the queries
$query1 = mysqli_query($con, $query1_string) or die(mysqli_error($con));
$query2 = mysqli_query($con, $query2_string) or die(mysqli_error($con));
$query3 = mysqli_query($con, $query3_string) or die(mysqli_error($con));
// Initializing the count
$count = 0;

//Making an array of strings including Rank, Name and Points of the Top 5 Players
while (($count < 5) && (mysqli_fetch_array($query3, MYSQL_NUM))) 
    $row = mysqli_fetch_array($query3, MYSQL_NUM);
    $results[$count] = $row[0] . "   " . $row[1] . "    " . $row[2];
    $count++;


// Dropping the view.
$end_query = mysqli_query($con, $query5_string) or die(mysqli_error($con));

//Returning the array
$leader = implode("\n", $results);
echo $leader;

【问题讨论】：

它显示的是偶数，你想显示奇数吗？

我想展示两者。 @яша

【参考方案1】：

您正在执行 query3 两次并显示从第二次执行中检索到的数据

while (($count < 5) && (mysqli_fetch_array($query3, MYSQL_NUM))) 
    $row = mysqli_fetch_array($query3, MYSQL_NUM);

【讨论】：

是的！就是这样。我被蒙蔽了:)谢谢