php - 迭代表中的列表值

Question

我有两个表，它们是连接在一起的，每个表的 ID 和下面的元素都是相似的。

parentID | objectName | subID            ID| className| subName |
_____________________________            ________________________
    84   |   Test     |   14             14|    BOM        |   Test
    84   |   More     |   16             14|    PDF        |   Test
    84   |   Sub      |   15             15|    Schematics |   Test2

我想列出相关元素的类别名称和子ID。几个ObjectNames将有几个相关的类。

PHP 代码:

$objects = mysqli_query($con,"SELECT * from subobject");


$join = mysqli_query($con, "SELECT * FROM subrelation AS subrelation INNER JOIN subobject AS subobject ON subobject.subId = subrelation.ID;");

echo "<ul>";
while($obj = mysqli_fetch_array($objects) and $row = mysqli_fetch_array($join))
{

    echo "<li>". $obj['objectName'];

    echo "<ul>";
    //ITERATION GOES HERE
    if($obj['objectName'] == $row['subName'])
        echo "<li>". "$row[className]" . "</li>";

    //END OF ITTERATION
    echo "</ul>";
    echo "</li>";
}   

echo "</ul>";

?>

和输出列表:

-Test
   -BOM
-Sub
  -Schematics
-More

每个字段下应该有更多列出的值。

Answer 1

看来您需要稍微简化一下代码。我的猜测是，您出现问题是因为每个结果集中的行数不同。这使得您的 while 循环在完成较小结果集(可能是 $objects)的处理后退出，即使较大集合中还有更多元素。

一种解决方案是对查询结果进行排序，在 while 循环中仅使用一个条件，并跟踪您当前正在使用哪个 objectName字符串$curr_objectName:

$join = mysqli_query($con, 'SELECT * FROM subrelation AS subrelation INNER JOIN subobject AS subobject ON subobject.subId = subrelation.ID ORDER BY subobject.objectName;');

$curr_objectName = '';

echo '<ul>';

while($row = mysqli_fetch_array($join)) {
    $subName = $row['subName'];

    if($subName != $curr_objectName)) {
        if($curr_objectName != '') {
            #close the previous list
            #will be skipped on the first loop iteration
            echo '</ul>';
            echo '</li>'; 
        }

        #start a new list
        $curr_objectName = $subName;

        echo '<li>'. $obj['objectName'];
        echo '<ul>';
    } else {
        echo '<li>'. $row['className'] . '</li>';
    }
}   

echo '</ul>';