Question

我有点像一个PHP菜鸟。

我正在尝试使用数组查询我的数据库，我正在尝试计算数据库中每个国家/地区查询返回的行数，并计算每个国家/地区的行数等于1.使用以下代码：

<?php

include ('mysqli_connect.php'); // indclude mysql connection functions

$countries = array('united states','canada','united kingdom');

foreach($countries as $country){
        //e.g. $r_spain holds the results from the query below with spain as $country
        $r_.$country = mysqli_query($dbc,"SELECT * FROM feelings WHERE country = '$country' AND digit='1'");

        //loop through the results
        while($row = mysqli_fetch_array($r_.$country, MYSQLI_ASSOC)){
                $rowCount = mysqli_num_rows($r_.$country);
                echo $country."=".$rowCount;   
        }      
}

?>

这是我收到的错误消息：

可捕获的致命错误：类的对象 mysqli_result无法转换串入 /home2/designwr/public_html/uwe/notalone/updates/percentage.php 第9行

任何人都能指出我正确的方向吗？

谢谢，alsweeet

Answer 1

您正在为变量名使用字符串连接：$r_.$country是两个字符串一起添加的结果。

我建议使用数组作为结果集：

$r = array();     // after $countries
....
    $r[$country] = mysqli_query......

Answer 2

Change:

$r_.$country

to:

${'r_'.$country}

删除循环（不是它的内容）：

while($row = mysqli_fetch_array($r_.$country, MYSQLI_ASSOC))

所以最后代码看起来像这样：

<?php

include ('mysqli_connect.php'); // indclude mysql connection functions

$countries = array('united states','canada','united kingdom');

foreach($countries as $country){
        //e.g. $r_spain holds the results from the query below with spain as $country
        ${'r_'.$country} = mysqli_query($dbc,"SELECT * FROM feelings WHERE country = '$country' AND digit='1'");
        $rowCount = mysqli_num_rows(${'r_'.$country});
        echo $country."=".$rowCount;   
}

?>

参考文献：

http://php.net/manual/en/language.variables.variable.php

http://www.php.net/manual/en/mysqli-result.num-rows.php

Answer 3

我认为第9行是

 $r_.$country = mysqli_query($dbc,"SELECT * FROM feelings WHERE country = '$country' AND digit='1'");

我不确定您要对$r_.$country = mysqli_query(...);做什么，但这是无效的语法。使用数组：

$r[$country] = mysqli_query(...);

Answer 4

查看mysqli/query上的手册。在那里，您将找到简单的工作示例，以便直接了解基础知识。计数由SQL请求中的count statement完成。

使用数组查询数据库

4 个答案: