创建每4个记录的列表

Question

我想创建多列表的记录与每个列表4记录而不知道有多少记录。但是，我无法弄清楚如何处理数学。我手动输入$ n == 5 || $ n == 9等知道它是有条件的，并不能完全解决问题。任何人都可以帮助我如何处理。而且，只有在记录总数不能被4除以4的情况下，下面的列表才能正常工作。如果可以，它将在最后创建一个空列表。

$query = "SELECT * FROM `table` WHERE `field` = $whatever"; 
if ($result = $con->query($query)){ 
$n = 1 
$row_cnt = $result->num_rows; 
$total_lists = round($row_cnt/4, 0); 
$current_list = 1; 
echo "<ul>List $current_list of $total_lists"; 
    while ($row = $result->fetch_assoc()) { 
    echo "<li>$row['something']</li>"; 
     if ($n == 5 || $n == 9 || $n == 13 || $n == 17 || $n == 21 || $n ==25 || $n ==29 || $n == 33 || $n == 37 || $n == 41 || $n == 45 || $n == 49 || $n == 53 || $n == 57 || $n == 61 || $n == 65 || $n == 69 || $n == 73 || $n == 77){ 
     echo "</ul>"; 
     $current_list = $current_list + 1; 
     echo "<ul>List $current_list of $total_lists"; 
     } 
    $n = $n + 1; 
    } 
echo "</ul>"; 
} 

在此先感谢您的帮助。 :)

解决：

$query = "SELECT * FROM `table` WHERE `field` = $whatever"; 
if ($result = $con->query($query)){ 
$n = 0 
$row_cnt = $result->num_rows; 
$total_lists = ceil($row_cnt/4); 
$current_list = 1; 
echo "<ul>List $current_list of $total_lists"; 
    while ($row = $result->fetch_assoc()) { 
     $n++; 
    echo "<li>$row['something']</li>"; 
     if ($row_cnt > 4) { 
    if ($n % 4 === 0) { 
    echo "</ul>"; 
    $current_list = $current_list + 1; 
    echo "<ul>List $current_list of $total_lists"; 
     } 
     } 
    } 
echo "</ul>"; 
} 

Answer 1

你其实并不是太遥远的轨道，从你可能想干什么，你只需要使用一个额外的工具来完成它：在%或模运算符。

模数运算符将返回除法问题的其余部分：

$x = 5 % 2; // 1 

在你的逻辑寻找，你的动作需要采取当你的增量器（$n）减1除以4将具有的0剩余：

if (($n - 1) % 4 === 0) 
{ 
    //your <ul> insertion could go here. 
} 

下面是PHP手册页面的链接讨论数学运算：

http://us1.php.net/manual/en/language.operators.arithmetic.php

Answer 2

或者，您可以在数据库结果上使用简单的array_chunk()。提供适当的分组（在本例中为四），并通过foreach循环它们。考虑这个例子：

// dummy data (values from db) 
$values_from_db = array(
    array('id' => 1, 'something' => 'list1'), 
    array('id' => 2, 'something' => 'list2'), 
    array('id' => 3, 'something' => 'list3'), 
    array('id' => 4, 'something' => 'list4'), 
    array('id' => 5, 'something' => 'list5'), 
    array('id' => 6, 'something' => 'list6'), 
    array('id' => 7, 'something' => 'list7'), 
    array('id' => 8, 'something' => 'list8'), 
    array('id' => 9, 'something' => 'list9'), 
); 

$values_from_db = array_chunk($values_from_db, 4); // group them by four's 

?> 

<?php foreach($values_from_db as $key => $value): ?> 
    <ul style="list-style-type: none;"> 
    <?php foreach($value as $index => $element): ?> 
     <li><?php echo $element['id'].'.'.$element['something']; ?></li> 
    <?php endforeach; ?> 
    </ul> 
<?php endforeach; ?>