查询中的SQL查询（PHP）

Question

So I've got myself some php below that is intended to find the columns of the spikes table and build an html table accordingly with the results of the spikes query.

Naturally, I don't want to be running a query for each loop, so I defined $schema to query it before the loops. However, if i don't declare it within the while($spike...) section, it just doesn't work. What am I doing wrong here?

And please do not give me a proprietary response. I'm trying to stick to writing code as cross-compatible between sql solutions as possible.

// Queries
$q_spikes = "SELECT * FROM spikes";
$q_schema = "SELECT * FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = N'spikes'";


// Table
echo "<table>";

    echo "<tr>";
    $schema = $conn->query($q_schema);

    while($info = $schema->fetch_assoc()) {
        echo "<td>" . $info['COLUMN_NAME'] . "</td>";
    }
    echo "</tr>";

    $spikes = $conn->query($q_spikes);

    while($spike = $spikes->fetch_assoc()) {

        echo "<tr>";

        $schema = $conn->query($q_schema);

        while($info = $schema->fetch_assoc()) {
            echo "<td>" . $spike[$info['COLUMN_NAME']] . "</td>";
        }
        echo "</tr>";

    }

echo "</table>";

Answer 1

Based on RiggsFolly's comment, I was able to achieve my goal with this:

    // Queries
    $q_spikes = "SELECT * FROM spikes";
    $needshead = true;

    // Table
    echo "<table>";
        $spikes = $conn->query($q_spikes);
        while($spike = $spikes->fetch_assoc()) {
            if($needshead) { 
                $needshead = false;
                echo '<tr>';
                    foreach ($spike as $key => $value) {
                    echo '<td>' . $key . '</td>';   
                    }
                echo '<tr>';
            }
            echo "<tr>";
                foreach ($spike as $key => $value) {
                    echo "<td>" . $value . '</td>'; 
                }
            echo "</tr>";
        }
    echo "</table>";