php - 查询为空，为什么？

Question

这是我的代码：

<?php
    $_SETTINGS = $GLOBALS["_SETTINGS"];
    $trigger = $_SETTINGS->fields->trigger->value;
    echo $trigger . " = " . $_GET[$trigger] . "</br>";
    $townQry = "SELECT * FROM towns WHERE id = '" . $_GET[$trigger] . "'";
    echo $townQry . "</br>";
    $result = mysql_query($cityQry) or die('Could not retreive towns: ' . mysql_error());

    while ($town = mysql_fetch_assoc($result)) {
        echo $town["town_name"];
    }
?>

这就是它的回声：

town_id = 2
SELECT * FROM towns WHERE id = '2'
Could not retreive towns: Query was empty

SQL 不是有效的...！？

Answer 1

您$cityQry在查询中使用，但查询在$townQry.

$result = mysql_query($townQry) or die('Could not retreive towns: ' . mysql_error());

额外的

您的查询对 sql 注入开放，我建议您使用 Google 准备好的语句。

Answer 2

您正在调用查询：

mysql_query($cityQry)

但是您的查询变量名为$townQuery.

它应该是：

mysql_query($townQuery)