如何在回声中放置一个onlick函数

Question

如何设置onclick功能echo "<td>" . $row['norm_name'] . "</td>"; 单击它时，应打开一个模态，您可以从中选择一个选项，为该行指定一个外键。我该怎么做

$sql = "SELECT norm_name FROM Norm WHERE theme_id IS NULL";
    if($result = mysqli_query($link, $sql)){
        if(mysqli_num_rows($result) > 0){

    echo "<table>";
        echo "<tr>";
            echo "<th>Norm</th>";
        echo "</tr>";

    while($row = mysqli_fetch_array($result)){
        echo "<tr>";
            echo "<td>" . $row['norm_name'] . "</td>";
        echo "</tr>";
    }
    echo "</table>";

    // Free result set
    mysqli_free_result($result);
}