PHP-如何在ifset条件中嵌套while循环？

Question

I have this table element with the following code:

<?php
if(isset($_POST["submit"])){
    if (strlen($cIdMsg = 0) && strlen($cFirstNameMsg = 0) && strlen($cLastNameMsg = 0) && strlen($pCodeMsg = 0)) {
        require_once("conn.php");
        $sql2 = "SELECT * FROM customer;";
        $results = mysqli_query($conn, $sql2)
        or die ('Problem with query' . mysqli_error($conn));
        echo "no errors found";
    }
}
?>

<table>
<tr>
    <th>Customer ID</th>
    <th>FIrst Name</th>
    <th>Last Name </th>
</tr>

<?php
    while ($row = mysqli_fetch_array($results)) { ?>
    <tr>
        <td><?php echo $row["customerID"]?></td>
        <td><?php echo $row["firstName"]?></td>
        <td><?php echo $row["lastName"]?></td>
    </tr>
<?php } ?>
</table>

Above this table I have the php code that makes the sql queries inside an if isset condition so that it only loads after pressing submit on the form. I would like to do the same to the table. That is to only make it load after pressing submit. because on page load it is trying to do the mysqli_fetch_array on a non existent $result yet

Answer 1

Wrap the whole table inside:

<?php if (isset($result)) { ?>
<table>
<tr>
    <th>Customer ID</th>
    <th>FIrst Name</th>
    <th>Last Name </th>
</tr>

<?php
    while ($row = mysqli_fetch_array($results)) { ?>
    <tr>
        <td><?php echo $row["customerID"]?></td>
        <td><?php echo $row["firstName"]?></td>
        <td><?php echo $row["lastName"]?></td>
    </tr>
<?php } ?>
</table>
<?php } ?>

I have used isset($result) based on what you have said. You can check for the POST values by checking for count($_POST) , or something similar ( not a good idea to check for isset($_POST["submit"]) ). If you are fetching for AJAX Response, it is always better to use a different separate file for this.

Answer 2

<?php if(mysqli_num_rows($result)!=0) { ?>
<table>
<tr>
    <th>Customer ID</th>
    <th>FIrst Name</th>
    <th>Last Name </th>
</tr>

<?php
    while ($row = mysqli_fetch_array($results)) { ?>
    <tr>
        <td><?php echo $row["customerID"]?></td>
        <td><?php echo $row["firstName"]?></td>
        <td><?php echo $row["lastName"]?></td>
    </tr>
<?php } ?>
</table>
<?php } ?>