PHP Array 包含太多元素答案

【问题标题】：PHP Array is carrying too many elementsPHP Array 包含太多元素
【发布时间】：2013-04-23 12:23:45
【问题描述】：

<?php
$query = "SELECT name FROM prodGroups";
$result = mysql_query($query);
$prodGroups = array();
while ($row = mysql_fetch_array($result, MYSQL_ASSOC)) {
    $prodGroups[] = $row['name'];
}
if (count($prodGroups) == 0) // IF NO PRODUCT GROUPS EXIST
    for ($j=1 ; $j<4 ; $j++)
    {
        echo "<li><a href='#'><span>Empty product group " . $j . "</span></a></li>";
    }
else // FOR WHEN PRODUCT GROUPS DO EXIST
    foreach ($prodGroups as $aGroup) // CYCLE THROUGH PRODUCT GROUPS
    {
        echo "<li class='submenu'><a href='#'><span>" . $aGroup . "</span></a>";
        $query = "SELECT name FROM products WHERE prodGroup='$aGroup'";
        $result = mysql_query($query);

        for ($j=0 ; $j<count($prodGroups) ; ++$j)
        {
            while ($row = mysql_fetch_array($result, MYSQL_ASSOC)) // PLACE PRODUCTS INTO AN ARRAY
            **{
                $products[] = $row['name'];
            }**
            if (!isset($products)) // IF THERE ARE NO PRODUCTS INSIDE A PRODUCT GROUP
                echo "<ul><li><a href='#'><span>No products</span></a></li></ul></li>";
            else // FOR WHEN PRODUCT(S) DO EXIST INSIDE A PRODUCT GROUP
            {
                echo "<ul>";
                if(isset($products))
                    foreach ($products as $item) // CYCLE THROUGH PRODUCTS
                    {
                        echo "<li><a href='#'><span>" . $item . "</span></a>";
                    }
                echo "</ul></li>";
            }
        }
    }

?>

在哪里$products[] = $row['name'];它携带所有元素，而我只是希望它携带产品名称到它们与 prodGroup 名称匹配的位置？我尝试使用 unset() 删除循环中的数组内容，但是这只允许每个循环中的数组中有一个元素。

【问题讨论】：

您可以使用 mysql_num_row($result) 来测试数据。然后在 while 中进行处理而不是构造 $products （即 echo '
...';

【解决方案1】：

添加$products = array(); 紧接着：

   foreach ($prodGroups as $aGroup) // CYCLE THROUGH PRODUCT GROUPS
    {

【讨论】：

太棒了，不敢相信这是这么小的东西。我以为数组在我分配 '$row['name']' 时就已经定义了。还有很多学习要做！非常感谢，非常感谢！
@user2324069：很高兴为您提供帮助，伙计 :)
@user2324069 - 如果您希望进一步提高该页面的性能，您可以使用更复杂的查询在 MySQL 端进行更多此类处理。

【解决方案2】：

我试图重写你的循环，修复了几个问题，其中大部分都是小问题。我评论了我的更改。看看这是否适合你。

foreach ($prodGroups as $aGroup) // CYCLE THROUGH PRODUCT GROUPS
    {
        echo "<li class='submenu'><a href='#'><span>" . $aGroup . "</span></a>";
        $query = "SELECT name FROM products WHERE prodGroup='$aGroup'";
        $result = mysql_query($query);

        //for loop here has been taken out
            while ($row = mysql_fetch_array($result, MYSQL_ASSOC)) // PLACE PRODUCTS INTO AN ARRAY
            {
                $products[] = $row['name'];
            }
            if (!isset($products)) // IF THERE ARE NO PRODUCTS INSIDE A PRODUCT GROUP
                echo "<ul><li><a href='#'><span>No products</span></a></li></ul>";
            else // FOR WHEN PRODUCT(S) DO EXIST INSIDE A PRODUCT GROUP
            {
                echo "<ul>";
                //if(isset($products)) - You already checked this..
                    foreach ($products as $item) // CYCLE THROUGH PRODUCTS
                    {
                        echo "<li><a href='#'><span>" . $item . "</span></a></li>"; //Don't forget to close this li
                    }
                echo "</ul>";
            }
            echo '</li>'; //close li here
            unset($products); //unset $products for next loop iteration

    }

当然，请不要使用已弃用的 mysql 扩展。请参阅@FreshPrinceOfSO 的评论。

【讨论】：

这些 cmets 和更改对我来说非常有价值，再次感谢！

【解决方案3】：

这应该让你明白我使用mysql_num_rows()是什么意思

<?php
$query = "SELECT name FROM prodGroups";
$result = mysql_query($query);

if( (!$result) || (mysql_num_rows($result) == 0) )// IF NO PRODUCT GROUPS EXIST
{
    for ($j=1 ; $j<4 ; $j++)
    {
        echo "<li><a href='#'><span>Empty product group " . $j . "</span></a></li>";
    }
}
else // FOR WHEN PRODUCT GROUPS DO EXIST
{
    while($row = mysql_fetch_array($result, MYSQL_ASSOC)) // CYCLE THROUGH PRODUCT GROUPS
    {
        echo "<li class='submenu'><a href='#'><span>" . $row['name'] . "</span></a>";
        $query2 = "SELECT name FROM products WHERE prodGroup='".mysql_real_escape_string($row['name'])."'";
        $result2 = mysql_query($query2);
        if( (!$result2) || (mysql_num_rows($result2)==0) )
        {
            echo "<ul><li><a href='#'><span>No products</span></a></li></ul>";
        }
        else
        {
            echo "<ul>";
            while ($row2 = mysql_fetch_array($result2, MYSQL_ASSOC)) // PLACE PRODUCTS INTO AN ARRAY
            {
                echo "<li><a href='#'><span>" . $row2['name'] . "</span></a></li>";
            }
            echo "</ul>";
        }
        echo "</li>";
    }
}
?>

【讨论】：