foreach 中的 php foreach

Question

我想要实现的是能够像这样打印结果：

Header 1
    Link 1
    Link 2
Header 2
    Link 3
Header 3
    Link 4
    Link 5

但是下面的代码打印结果像这样：

Header 1
    Link 1
    Link 2
Header 2
    Link 1
    Link 2
    Link 3
Header 3
    Link 1
    Link 2
    Link 3
    Link 4
    Link 5

使用 php pdo 包装类，据我所知，我别无选择，只能使用“foreach”而不是“while”来循环结果，这是我的代码:

$bind = array(":users_id" => $id);
$categoryQry = $db->select("category","users_id=:users_id", $bind);
//loop Headers
foreach($categoryQry AS $CatRes){
    $category_name = $CatRes['category_name'];

    $bind = array(
        ":users_id" => $id,
        ":link_category" => $CatRes['category_id']
    );
    $linkQry = $db->select("links", "users_id=:users_id AND link_category=:link_category", $bind);
    //loop Links under each header
    foreach($linkQry AS $LinkRes){
        $link_url = $LinkRes['link_url'];
        //$link_row outputs the links under each header, this is where the problem is        
        $link_row .= DisplayLayout("link_row.html","\$link_url");
    }

    //$header outputs the result OK (3 headers as stated in above example)    
    $header .= DisplayLayout("header.html","\$category_name,\$link_row");
}
//note that DisplayLayout is my template function which is used for outputting variables using an HTML file.

我一直在尝试其他一些方法，但没有运气，希望有人会发现我的代码中的问题并引导我走向正确的方向。

预先感谢您，圣诞快乐。

Answer 1

您需要在此行之前重置 $link_row：foreach($linkQry AS $LinkRes)

Answer 2

$bind = array(":users_id" => $id);
$categoryQry = $db->select("category","users_id=:users_id", $bind);
//loop Headers
foreach($categoryQry AS $CatRes){
$category_name = $CatRes['category_name'];

$bind = array(
    ":users_id" => $id,
    ":link_category" => $CatRes['category_id']
);
$linkQry = $db->select("links", "users_id=:users_id AND link_category=:link_category", $bind);
//loop Links under each header
$link_row='';
foreach($linkQry AS $LinkRes){
    $link_url = $LinkRes['link_url'];
    //$link_row outputs the links under each header, this is where the problem is        
    $link_row .= DisplayLayout("link_row.html","\$link_url");
}

//$header outputs the result OK (3 headers as stated in above example)    
$header .= DisplayLayout("header.html","\$category_name,\$link_row");
}
//note that DisplayLayout is my template function which is used for outputting     variables using an HTML file.

Answer 3

//reset linkrow
$link_row = '';


foreach($linkQry AS $LinkRes){
    $link_url = $LinkRes['link_url'];
    //$link_row outputs the links under each header, this is where the problem is        
    $link_row .= DisplayLayout("link_row.html","\$link_url");
}

Answer 4

在第二次循环之前清空 $link_row。