php - 如果没有数据，如何隐藏列

Question

我有一个从数据库中提取信息的表。为了让访问网页的人看起来整洁，我希望在没有信息的情况下隐藏一些列。

我的表格列出了全年赛车运动的结果。年初时只会有 1 个事件，但到 12 月时将添加 20 多个结果。因此，我希望隐藏它们，直到添加该事件的标题，而不是有大量空列。

我尝试使用 !empty 但这并没有像我想要的那样工作。它只是将空行移到左侧，导致标题与正确的结果不匹配。

这是我的代码:

<?php
//MySqli Select Query
$results = $mysqli->query("SELECT *, (u181 + u182 + u183 + u184 + u185 + u186 + u187 + u188 + u189 + u1810 + u1811 + u1812 + u1813 + u1814) AS total FROM results WHERE u18 = '1'");
$title = $mysqli->query("SELECT * FROM closedevents");

while ($t = $title->fetch_assoc()){
echo "<table width=\"1000\" border=\"0\" cellpadding=\"5\" cellspacing=\2\" class=\"entrywriting\" align=\"center\">
<tr align=\"center\">
<td>Overall</td>
<td>Competitor</td>
<td>" . $t["u18a"] . "</td>
<td>" . $t["u18b"] . "</td>
<td>" . $t["u18c"] . "</td>
<td>" . $t["u18d"] . "</td>
<td>" . $t["u18e"] . "</td>
<td>" . $t["u18f"] . "</td>
<td>" . $t["u18g"] . "</td>
<td>" . $t["u18h"] . "</td>
<td>" . $t["u18i"] . "</td>
<td>" . $t["u18j"] . "</td>
<td>" . $t["u18k"] . "</td>
<td>" . $t["u18l"] . "</td>
<td>" . $t["u18m"] . "</td>
<td>" . $t["u18n"] . "</td>
<td>Total</td>
</tr>";
}

//set counter
$counter = 1;
while($row = $results->fetch_assoc()) {
    echo "<tr align=\"center\">";
    echo "<td>" . $counter . "</td>";
    echo '<td>'.$row["competitor"].'</td>';
    echo '<td>'.$row["u181"].'</td>';
    echo '<td>'.$row["u182"].'</td>';
    echo '<td>'.$row["u183"].'</td>';
    echo '<td>'.$row["u184"].'</td>';
    echo '<td>'.$row["u185"].'</td>';
    echo '<td>'.$row["u186"].'</td>';
    echo '<td>'.$row["u187"].'</td>';
    echo '<td>'.$row["u188"].'</td>';
    echo '<td>'.$row["u189"].'</td>';
    echo '<td>'.$row["u1810"].'</td>';
    echo '<td>'.$row["u1811"].'</td>';
    echo '<td>'.$row["u1812"].'</td>';
    echo '<td>'.$row["u1813"].'</td>';
    echo '<td>'.$row["u1814"].'</td>';
    echo '<td>'.$row["total"].'</td>';
    echo "</tr>";
    $counter++; //increment count by 1
}  
echo "</table>";

?> 

因此，如果 u18j、k、l、m、n 中没有标题名称，那么这些列将不会显示在表格中。

Answer 1

PHP 替代方案:

<?php
//MySqli Select Query
$results = $mysqli->query("SELECT *, (u181 + u182 + u183 + u184 + u185 + u186 + u187 + u188 + u189 + u1810 + u1811 + u1812 + u1813 + u1814) AS total FROM results WHERE u18 = '1'");
$title = $mysqli->query("SELECT * FROM closedevents");

$all_cols=array("u18a" => "u181","u18b"=> "u182","u18c"=> "u183","u18d"=> "u184","u18e"=> "u185","u18f"=> "u186","u18g"=> "u187",
        "u18h"=> "u188","u18i"=> "u189","u18j"=> "u1810","u18k"=> "u1811","u18l"=> "u1812","u18m"=> "u1813","u18n"=> "u1814");

while ($t = $title->fetch_assoc()){
    // remember empty cols
    $empty_cols=array();

    echo "<table width=\"1000\" border=\"0\" cellpadding=\"5\" cellspacing=\2\" class=\"entrywriting\" align=\"center\">
    <tr align=\"center\">
    <td>Overall</td>
    <td>Competitor</td>";

    foreach ($all_cols as $col => $value) {
        if (!empty($t[$col])) {
            echo "<td>" . $t[$col] . "</td>";
        } else {
            // set this column as empty for later
            $empty_cols[]=$col;
        }
    } unset($col); unset($value);
    echo "
    <td>Total</td>
    </tr>";
}

//set counter
$counter = 1;
while($row = $results->fetch_assoc()) {
    echo "<tr align=\"center\">";
    echo "<td>" . $counter . "</td>";
    echo '<td>'.$row["competitor"].'</td>';

    foreach ($all_cols as $col => $value) {
        if (!in_array($col, $empty_cols)) {
            // echo non-empty values
            echo '<td>'.$row[$value].'</td>';
        }
    } unset($col); unset($value);

    $counter++; //increment count by 1
}  
echo "</table>";

?>